Did Paul invent Christianity?

This passage Shows that the Gospel is not something that someone would have invented to appeal to the culture of  the time:

For the preaching of the cross is to them that perish foolishness; but unto us which are saved it is the power of God.
For it is written, I will destroy the wisdom of the wise, and will bring to nothing the understanding of the prudent.
--1 Cor 18-19

For the Jews require a sign, and the Greeks seek after wisdom:
But we preach Christ crucified, unto the Jews a stumblingblock, and unto the Greeks foolishness;
--1 Cor 1:22-23


Here is a longer answer that shows that Paul, as a Pharisee, was working to preserve tradition:

The A, B, Cs . . . Ds Es of Defending the Gospels - Dr. Mike Licona