I have personally heard the objection that the Gospel of Jesus is just a rehashing of Pagan myths borrowed from the surrounding culture. Dr. Mike Licona (at Ottawa’s Dig & Delve Conference) gives an amazing rebuttal to this often given, but completely erroneous claim.
Note: For a more in-depth analysis on this, I recommend “Evidence That Demands a Verdict: Life-Changing Truth for a Skeptical World,” by Josh and Sean McDowell.
“Did early Christians borrow from Pagan myths” by Dr. Mike Licona
A Verse A Day 