You can use it, but it would be tippety-top if you used it correctly - i.e. not as part of a strawman argument or non sequitur.
Bart Ehrman's book claims that a man named Jesus existed. He definitely does not claim that any kind of divine Jesus existed. I personally don't think he's made a convincing case for the existence of the non-divine Jesus either, but then I have read the book in its entirety, and as far as I'm aware, you have not.
Every time you try to conflate Ehrman's support for the existence of "Jesus the non divine man" and your belief in the existence of "Jesus the divine Christ", you are misrepresenting Ehrman's book. It's been pointed out to you often enough that Ehrman states quite definitely that the Jesus of theologians and preachers did not exist; lying for Jesus may earn you Brownie points in church but it's frowned on here.