Sound exegesis of Scripture involves the cultural and environmental background, who wrote it, when and why he wrote it, and who were the ones the Scripture was directed to. There are Scriptures that were written for us, and others that were written to us. Sound exegesis helps us determine which is which.
Most of the Old Testament and the gospels were written for us, but not necessarily to us. The verse "Judas went out and hanged himself" is written for us to show the consequence of betraying Jesus and the overwhelming guilt such a person has that he cannot come to repentance and his only way out is suicide. But we also see that Judas did not have a full understanding of the grace of God, and forgiveness was there for him if he had fallen before God and sought mercy, because we see in another verse that "all sin and iniquity shall be forgiven of men." But the verse is not an instruction for us that if we become so overcome with guilt that we should go out and hang ourselves.
But in 1 Corinthians 1, we see that Paul wrote the letter not only to the Corinthian church, but to all Christians everywhere. This means that the letter is written to us, containing instructions and recommendations for us to follow.
Much of the teaching of Jesus in the gospels was to the unconverted Jews who were still under the law. That is why He approved when the rich young ruler told Him that he had followed the Commandments from his youth up. This is not a contradiction to Paul's teaching that no one is justified by observing the Law. It all hangs on when and who Jesus was speaking to, and when and who Paul was writing to. Jesus was speaking to Jews still under the Old Covenant where observing the Law and sacrifices was still the path to righteousness before God. Paul was writing to New Covenant folk who were born again of the Spirit of God, and who were given the righteousness of Christ.
The mistake that many do is to take Old Covenant Scriptures and directly apply them as instructions to New Covenant people. Old Covenant instructions involved an eye for an eye, but New Covenant is to forgive our enemies and not require retribution from them.
For these reasons, to fully understand Scripture, there needs to be the study of the environment, culture and audience to be able to determine what it meant to those who listened to it when it was first presented to them. When we do that, we discover that the particular Scriptures may not directly apply to us because we are not living in Old Testament Israel or during the time of Jesus in Judeah under Roman occupation. But we can learn much from them so we don't make the same mistakes as others did.
What I learned from Peter walking on the water to Jesus, was that all the other disciples never had to courage or faith to get out of the boat, when in fact, all of them could have got out of the boat and walked on the water to Jesus. Using hermeneutics (the skill of interpreting Scripture), we can determine for ourselves the level of our faith in Christ, and how much we actually do depend on the Lord when He calls us to a particular task for ministry. Are we prepared to "get out of boat" and start walking, or we grimly hanging on in the boat, too afraid to step out in faith and trust in the Lord?
