Christians, is it possible that Jesus didn't exist? Atheists and anyone else may respond.?

I cannot say with complete certainty that Jesus Christ did not exist but I am reasonably sure that he did not. There is no physical evidence to support Jesus Christ's existence. There are no eyewitness accounts, works of carpentry, self-written manuscripts, or Roman record of Pontius Pilate executing a man named Jesus Christ. All claims about Jesus Christ derive from writings of people who never met him and came well after he supposedly existed. On top of that, the concept of a messiah being born of a virgin mother is an allegory which has been recycled multiple times for at least 5,000 years, i.e. Horus was worshiped in Ancient Egypt as the Savior and was born from the virgin Isis. Please explain why you believe, with full assurance, that Jesus Christ existed.