If you believe in Christ you are a Christian. Over half the country falls into this category. Nobody cares about purity tests or grades. Keep them to yourself.
If you believe in Christ, you will follow Christ. There is the passage in John "I am the way ........no one comes to the Father but through me".
Following Christ means living for him , giving up my ways.
By that definition or "test" it seems there is likely a pretty narrow following, and few are finding it.
But there are many who are taking the broad path that leads, uh elsewhere, putting it nicely.
One interesting passage is Jesus warning of a time after life when many who thought they were living for him were not. They even claimed to have done many things in his name, but he tells them to get out of heaven ( the good place) for "I never knew you".
I dont think believing Jesus existed is the same as believing in him for salvation.
Last, "to him that knows to do good and does not do it, it is sin." To be clear, I know I dont do at times what a Christian is expected to do, and I know better. Not perfect, just forgiven as the saying goes.
Hey, I miss church.