Four Things That Will Help You Understand the New Testament
#1: The Old Covenant Law Was Never Given to the Gentiles
Many who teach law argue that they are defending righteousness against lawlessness. Whether they understand it or not, they are really robbing people of the faith that God established through New Covenant grace.
The Old Covenant Law was an external standard of righteousness that was given only to Israel. Since God's standard has always been perfect righteousness, failure at one point of the Law meant the violation of the entire Law (James 2:10). The Jews had nothing except their own best efforts to comply with the Law; failure was the result. So, if you try to present yourself to God as righteous by your own works, you too will fail.
The New Covenant removed the Law entirely; there is now no Law that a Jew or Gentile, believer or unbeliever, can violate. This is because God's perfect righteousness is no longer an external standard. Rather God joins His righteous life to those who trust in Jesus Christ as Savior. Believers are righteous in their born again hearts because God in them is righteous. Even so, believers cannot live righteously by their own efforts because only their new inner spirits have been redeemed and made righteous thus far (Romans 8:10). Believers live righteously when they live by faith, that is, when they follow the life that Jesus Christ is living in them as He does His good works through them (Galatians 2:20).
Several decades after Christ rose from the dead, the unity between Gentile Christians and Jewish Christians eroded and animosity ensued. The two groups separated. Later, as the Gentiles attempted to understand the books and letters that became the New Testament, they did so without comprehending their Jewish context. This led to the unbiblical mixture of two opposites, Old Covenant law, which is self-empowered living, and New Covenant grace, which is God-empowered living. The Gentiles were proclaiming a religion that they did not really understand.
The Bible, and the New Testament, were written by Jews*, primarily to Jews. Both the Old Covenant Law and the New Covenant were exclusive accords between God and Israel (Romans 9:4b; Hebrews 8:8). The Gentiles are "grafted" into and receive the benefits of the New Covenant (Romans 11:17) but the Gentiles never had any relationship with the Old Covenant Law. The Law was made for the flesh, not for a people who have been given the Holy Spirit.
The letters of Peter, John, James and the writer of Hebrews were all written specifically to Jewish believers. The letters of the Apostle Paul were written to mixed Gentile and Jewish audiences; several sections in Paul's letters were addressed specifically to Jewish issues. Galatians 1-5 is an example because the Apostle Paul speaks about believers turning back to the Old Covenant Law. Gentiles never had the Law, and they could not turn back to it; however, many were getting swept away by the false teaching that salvation required following the Law.
(*Luke was most likely a Gentile and, therefore, the only non-Jewish writer of the New Testament; both of his books, Luke-Acts, were written to a single individual, Theophilus.)
Now there is a near-universal failure to understand the Jewish context of the New Testament. It is also not understood that the Law ended before salvation ever came to the Gentiles (Hebrews 8:13; Romans 10:4). The tragedy is that Christians now live as if the Law is still in effect; they try to be righteous before God by their own human works. They miss entirely the indwelling life of Jesus Christ and are guilty of exactly what the Apostle Paul is charging in his letter to the Galatians (Galatians 3:2,3,11,12; 5:4).
For Bible verses showing that the Gentiles were never under the Law, Click Here. Also, read Hebrews 9:8-10:18; it explains that the Law was but a "shadow of the good things to come," namely Jesus Christ, and it explains the ending of the Law. Also, Romans 11 explains how the Gentiles have been "grafted" into a salvation that comes from the Jews (John 4:22).
#2: The New Testament Must be Understood in its Original Context
Proper context is key to understanding the Bible. Improper context is the root of most of the error being taught today and in the past. One way context is compromised is by "proof-texting" where a passage is removed from its surrounding context and used to say something that the Bible does not say. This is more common than you might think. For example, both "Christian" television and many churches use Malachi 3:10 to raise money; in reality, this verse is talking about food, not money.
But, the long-standing error of mixing Old Covenant law with New Covenant grace has caused even greater damage. The Law is not God's standard to live by because it was made for the flesh and based on human works (Galatians 3:12). The Law no longer exists. Faith is God's standard to live by because it is based on the indwelling power of the Holy Spirit (Galatians 3:11).
Those who teach the law do not see the real issue; it is not about righteousness vs. lawlessness. The central issue between Law and grace is how you live righteously, either by your own human power (law) or by the power of Christ living in you (grace).
Old Covenant Law = trying to establish righteousness through your own human performance
Also, the four Gospels are almost universally misunderstood. Jesus was teaching the Old Covenant Law to the Jews. Jesus was not teaching the Gentiles nor was He teaching New Covenant grace at that time. Although grace is evident in virtually every word and deed of Jesus, it was not until just before His arrest that He revealed New Covenant grace to His disciples in a way that they had not yet heard. John, chapters 14 through 17 are among the most dynamic chapters in all the Bible.
Jesus was born under Law (Galatians 4:4). He had to live sinlessly under the Law, go to the Cross and be raised from the dead before the New Covenant could even begin. After Jesus fulfilled every jot and tittle of the Law, God ended the Old Covenant and transitioned into the New Covenant (Hebrews 8:13). Only then were the Gentiles included (Romans 11:17) in a salvation that is from the Jews (John 4:22).
The context of the Bible, including the New Testament, is predominantly Jewish. If you understand this, you can understand that when the writers of the New Testament talked about the Law, they were not addressing the Gentiles. Sadly, mixing Law with grace has obscured the truth that righteousness and righteous living come through the power of Christ in you, not your own human endeavor.
#3: All People are Spiritual Being Living in Mortal (Physical) "Tents"
Your inner spirit, also known as your heart or nature, was redeemed and forever made righteous when God saved you. But your outer mortal body, which awaits a future redemption (Romans 8:23b), is still dead because of sin. This is explained in Romans 8:10.
Romans 8:10 If Christ is in you, though the body is dead because of sin, yet the spirit is alive because of righteousness.
Romans 8:10 Expanded: If Christ is in you (speaking to true believers indwelled by Jesus Christ), though the body is dead because of sin (because your physical body has not yet been redeemed or made righteous), yet the spirit is alive because of righteousness (because your born again heart has already been redeemed and made righteous).
Your inner spirit is the real, essential "you"; this means that you are saved because God put His own righteous and eternal life into your new born again heart. Here is way to understand this critical truth: when you die, your physical body will go to the grave because it has not yet been redeemed or made righteous; but your inner spirit continues to be, as it is right now, forever joined as one to Jesus Christ because it has already been redeemed and made righteous.
By your own human strength, you cannot live a righteous life pleasing to God since your mortal body is still dead because of sin. But, you can live a righteous life as you follow in faith the indwelling life of Jesus Christ.
Galatians 2:20 I was crucified with Christ; and it is no longer I who live, but Christ lives in me; and the life which I now live in the flesh, I live by faith in the Son of God, who loved me and gave Himself up for me.
#4: Jesus Emptied Himself to Live Fully as a Man "For a Little While" During His Time on the Earth
This next truth is, by far, the hardest for Christians to accept. But, truth is what God teaches you, not what human tradition teaches you. Since the 4th and 5th centuries, a non-Biblical version has been taught of who Jesus Christ really was when He lived on this earth. Yet, if you simply believe what the Bible says, a whole new world of understanding will open up to you.
Jesus Christ is the Son of God and the Creator of the Universe. He is sovereign over all things and creator of all things. The Bible is clear on this teaching.
Jesus is God: Isaiah 9:6 For a child will be born to us, a son will be given to us; And the government will rest on His shoulders; and His name will be called Wonderful Counselor, Mighty God, Eternal Father, Prince of Peace.
Jesus is the Creator: Colossians 1:16 For by Him (Jesus) all things were created, both in the heavens and on earth, visible and invisible, whether thrones or dominions or rulers or authorities - all things have been created through Him and for Him.
Although the "fully God-fully man" teaching is one of the most ingrained teachings in institutional Christianity, it is not what the Bible teaches. Jesus emptied Himself "for a little while" to live fully as a human while on this earth so that He could complete the work of the Father.
Hebrews 2:9 But we do see Him who was made for a little while lower than the angels, namely, Jesus, ... so that by the grace of God He might taste death for everyone.
People are afraid to believe that Jesus was fully man while on the earth because of the persistent and automatic charge that it denies His deity. Believing that Jesus emptied Himself in no way denies His deity because He "who was made for a little while lower than the angels" must be He who is higher than the angels, namely Jesus, the Son of God.
Instead of being fully God and fully man at the same time, Jesus was fully man indwelled by the Holy Spirit. The reason that this distinction is important is that Deity cannot be tempted by sin as Jesus was (James 1:13). Also, God made the sinless Jesus to be sin so that we might be made righteous through Him (2 Corinthians 5:21). And, Jesus had to be fully man so that He could be a merciful High Priest and so that He could die for the sins of the people (Hebrews 2:17). To save you, Jesus became "the Son of Man."
Additionally, since death spread to all humankind through a man, Adam, it was therefore necessary that death be conquered through a man by the resurrection from the dead.
1 Corinthians 15:21 For since by man came death, by a man also came the resurrection from the dead.
Jesus had to empty Himself to be fully human so that He could die on the Cross (to defeat sin) and be raised from the dead (to conquer death).
The reason that people don't believe what the Bible teaches is because human reasoning got in the way of faith. People could not resolve the question, "How can God stop being God?" The doctrine of hypostatic union ("fully God-fully man") says that Jesus had the full power of God within Himself but He chose not to exercise His prerogatives as God. But in reality the Bible teaches that Jesus emptied Himself.
Philippians 2:5-8 Have this attitude in yourselves which was also in Christ Jesus,  who, although He existed in the form of God, did not regard equality with God a thing to be grasped,  but emptied Himself, taking the form of a bond-servant, and being made in the likeness of men.  Being found in appearance as a man, He humbled Himself by becoming obedient to the point of death, even death on a Cross.
Jesus did not have the full power of God within Himself since He emptied Himself. Rather, it was the Holy Spirit who came down and indwelled Jesus at His baptism (Luke 3:22) in order to be His power to do the works of God. Jesus did not do these works and miracles by His own human power (John 5:30; 8:28); it was the Father in Him who did these works.
John 14:10b (Jesus speaking) "... I do not speak on my own initiative, but the Father abiding in me does His works."
This is the critical point because the fully God-fully man teaching obscures the most important truth that every believer must understand in order to live a life of faith: the same Holy Spirit that indwelled and empowered Jesus now lives in you and is your power to live righteously and to do the good works that God has in store for you. Religion has robbed believers of understanding that Jesus became like us so that we could live the same life of faith that He did.
As a believer, you have the very same power to live life that Jesus had (2 Peter 1:4; 1 Corinthians 3:16). Jesus lived by faith; so can you. Jesus did not do any of the works the Father had given Him apart from the power of the Holy Spirit in Him. You, in turn, cannot do any good works or live righteously apart from the Holy Spirit living in you.
Note: To read more than 25 verses that speak of Jesus being fully human while here on this earth, Click Here. Also, there is not a single verse in Scripture that teaches the "hypostatic union" of Jesus Christ. Two verses in Colossians that speak of the Father indwelling Jesus are often misinterpreted as "proving" the hypostatic union (Colossians 1:19, 2:9).