‘Christianity is irrational’

I was debating someone on Reddit yesterday,  and this gem fell into my lap. Here’s the full text, if anyone is interested. 
The guy said that ‘Christianity is irrational because it is a belief based on faith.’ And anything based on faith is irrational.
So I asked him if he had any proof that God didn’t exist. Of course, he didn’t.
So I asked if his worldview included a God. Of course it didn’t.
So while he assumed Christianity was irrational because it was based on faith (incorrectly), I showed that his worldview was similarly based on the nonexistence of God. With no proof.
So if a belief is irrational because it is based on faith, atheism is faith that God does not exist, with no reasons to believe so.