I have a Presbyterian origin, my parent were never practicing except for births deaths and marriages; in those days' religions were required for identity. Apart from what Presbyterians teach to eight-year old's, I never knew what they taught; I did hear while in high school some of their criticism of the RCC. I have always regarded myself to be a Christian.
Rationalizing Paul as a deceiver began ten after the fact, using SDA metaphor, a door was definitely shut.
I have heard Seminary types question Paul, say things like, all women have to do to be saved is to have babies, and those with the different gospel that Paul threatened to curse, were Peter and James and others from the Jerusalem church, I have not heard anyone other than myself call him a deceiver. Deceiver is a conclusion I reach after being told to disregard him.
“It reaches a point as to why bother being Christian” What is a Christian? Is Paul required in the definition? What does the word “synoptic mean to you? I am not familiar with religious jargon. Even apart from Paul, I always allow that the NT has been edited and is only true when it complies with the OT as a second witness. If Paul had never happened, would it then be possible to follow Christ?
Hypothetically, if the angel of light that sent Paul was Satan, then Paul's actions against the Pagans mentioned in Acts would be enough to convert Goebbels. The deceiver had to be good enough to deceive the very elect.
How would one test an apostle, Rev 2:2, it vary with the situation, I believe, if the apostle was ten times taller than Christ and more important he would need to be introduced early in Genesis, and in every other book, i.e. Paul in all the scriptures. For me, given his importance and the worship he receives, I would need to be forewarned of Paul at least once in the OT prophesies.