I have found that reading additional books adds to that Bible knowledge you are speaking about.
I agree, but our basic source should be scripture
whatever we read, it has to agree with what the Bible plainly says.
Concerning Peter, Paul directly contradicts any claims that Peter was the apostle to the gentiles, even though Acts chapter 10 shows him being the first one to bring the gentiles into this, Paul plainly states Paul is the apostle to the Gentiles while Pete is the apostle to the Jews
To make a doctrine that is the opposite or contradictory..well, it might be what a person thinks, but it aint Biblical.