My Bible professor at Providence Christian College was Dr. Scott Swanson. These are six important things I learned from him (although this is by no means an exhaustive list).
1. Sanctification is as important as justification. At the same time, the two doctrines cannot be conflated or we lose the basis of our salvation (justification) and the basis of working out our salvation with fear and trembling (sanctification). Because of justification we have a right standing with God (we are “accounted righteous”), and the fuel for our sanctification is the new birth in the Spirit. When we get to heaven, the only reason we are there is because of the imputed righteousness of Christ, but this in no way makes us antinomians. Jesus saved us for good works which God prepared in advance for us to do. These works are not optional, but neither do they add anything to our right standing with God. Our justification and sanctification are both works of God in our hearts. There is a logical order to the two doctrines (justification comes before sanctification), but they are both necessary for the Christian.
2. When Paul talks about the ‘mystery’ of the gospel (i.e. Ephesians 3:4,6), it is meant in the sense of ‘secret’. The Greek word μυστήριον should be conveyed as ‘secret’ because the gospel was kept hidden in the Old Testament (in types, antitypes and shadows) and then set forth in the fullness of time in the New Testament teaching of the Apostles. The gospel “…has now been disclosed and through the prophetic writings has been made known to all nations, according to the command of the eternal God…” (Romans 16:26). As Dr. Swanson wrote to me recently, the better translation of the Greek word as ‘secret’ is “…full of implications for our exegesis and theology. First of all, we thus see that the point being made has nothing to do with "mysteriousness," but rather in fact that this amazing content of the gospel and God's redemptive plan is revealed/made known to us. And also of course, it warrants for us finding this plan in the OT, where it lay in some sense hidden until the revelation in the NT (thus especially the Rom. 16 passage, which specifies that through the apostolic teaching/preaching, this message is now being made known from the OT prophets).”
3. We cannot take an English cognate of a Koine Greek word and assume the English meaning back into it. For example, it is popular for pastors to say that the Greek word δύναμις (meaning ‘power’ in the Greek) is where we get the English word dynamite. Therefore, when Paul says that he is not ashamed of the gospel “…for it is the power of God for salvation to everyone who believes…” (Romans 1:16, emphasis mine), many pastors will say that the gospel is the dynamite of God. The obvious problem is that we have taken our English word and read back in a meaning that was never in the mind of Paul. We can be sure Paul did not know what dynamite was!
4. The meaning of Romans 8:1-4 can be defended as either talking about our justification or sanctification. If one pays close attention to the context and flow of the passage, we find that it is actually talking about our sanctification. The key to this understanding is verse 4, which talks about the righteous requirement of the law being fulfilled in us. Since justification is extra nos, that is, outside of us and not based on any change in us, then Paul must be referring to sanctification. In verse 3, when it says that Jesus condemned sin in the flesh, it means God did what the law could not do. The law actually aroused sin in us and could not make us obey. By God sending Christ in the flesh he killed the power of sin in us so that we can achieve real victory over sin in our lives, and actually begin to obey God’s law (albeit not perfectly). Because we are in the Spirit, the implication of the passage is that we can now submit to God’s law (although we do not rely on the Spirit perfectly). This reading of Romans 8 has profound implications for our obedience to God.
5. The church has three purposes. The worship and praise of God, the nurture of believers, and evangelism. You can see the problem if one of the latter two purposes is set higher than the others. In churches where only the nurture of believers is focused on, you have a church not worried or caring about the lost, and not fulfilling Jesus’ own purpose of coming to seek and to save that which was lost. If you set evangelism as the goal over and above the nurture of believers, then you have a whole church that is satisfied on milk, and not on true gospel and spiritual meat, not growing in the knowledge of God and his ways.
6. The hermeneutical spiral means that as we learn things about Scripture, we are constantly correcting our presuppositions about the world. It also means that as we learn about and find truth in the world, we are constantly correcting our faulty views of Scripture. This allows us not to make the same mistakes the church made in thinking that everything in the solar system revolved around planet earth, contra the findings of Galileo who said (rightly) that the earth actually revolved around the sun. We are called to find truth in both general and specific revelation, because Jesus is Lord of every square inch.