Arguing that Christ was not real is just ignorant.

The Council of Jerusalem was around the year 50 AD, only 17 years after the death of Christ.

By then, there was real in-fighting among the Christians.

As early as 22 years after the death of Christ, Paul wrote letters to the followers of Christ. Even if you disregard his opinions, it is hard to argue that he is writing to imaginary people.

These earliest letters were to a slave owner named Philemon, the church of the Thessalonians, the saints (believers) in Phillippi, the church in Corinth, the churches in Galatia (more than one), and to the believers in Rome.

These people knew that Christ was real. They all lived during His time, even though Paul never met Him in the flesh.

Greek and Roman mythology was not overcome by another myth. Whole civilisations have left their fairy tales in favor of the living GOD.