Such as?

Some points to consider.

1. Paul supposely spent the first 3 years in Arabia after his conversion, which was also before he went to Jerusalem the first time. He also supposedly spent 9 years in Tarsus. Why? Is it possible that he was struggling to understand the things that Jesus was telling him, which, by the way, were not "face to face" like Jesus had taught the other Apostles?

2. As far as we know, Paul wasn't present for any of Jesus' verbal teachings to the Apostles while He was alive. AND we don't know just how much the Apostles had told Paul. The ramifications of this are huge.

3. The last few chapters of Acts focus more on where Paul went and what happened than what he was actually teaching on those trips. We don't know exactly what Paul taught, but the fact that he had already been to Jerusalem and spoke with the others before his journeys, and their acceptance of him, is telling.

4. All of Paul's letters were to congregations that he had already established, and therefore each one is specific to problems within each of those congregations. The letters weren't addressed to "all the churches" as uniform teachings. Trying to construct a "theological base" from them is a daunting task which many experts can even disagree on.

5. Paul's letters were addressed to congregations that had relatively large percentage of Gentiles. This makes it difficult to compare what he taught as compared to what the other Apostles taught, which we also don't have much of a record of. The Gentile "base" of those groups would also cause Pauls' "approach" (and possibly even Jesus' instructions concerning such) to be different. A great example of this is Paul's sermon in Athens about the "unknown God" in Acts 17.

6. John's and Peter's letters were also to previously established "churches". Their not exactly the same as Paul's for good reason, yet there are similarities.

7. Paul didn't have the "luxury" like we do of reading the 4 Gospels before he went preaching. And the Gospels don't tell us WHAT & HOW the Apostles taught, they focus on what Jesus taught others and them. Chances are quite good that Paul wrote his letters before the Gospels, as Peter's letter states this...

2 Peter 3

15 And account that the longsuffering of our Lord is salvation; even as our beloved brother Paul also according to the wisdom given unto him hath written unto you;

16 As also in all his epistles, speaking in them of these things; in which are some things hard to be understood, which they that are unlearned and unstable wrest, as they do also the other scriptures, unto their own destruction.

Lastly, Paul's journeys to "plant churches" always started at Jewish synagogues that were in large Gentile populations. He dealt with not only radical Jews who refused the Gospel, but also with radical pagans who refused to give up their idolatrous sinful ways.

What I see in Paul's letters as far as teachings...

A. Repentance for remission of sin.
B. Jesus was the Son of God.
C. Jesus died on the cross and was resurrected.
D. Belief of those things, and leading a sinless life, would end up in Salvation.