Let’s see your article stating he is an unbeliever. You’re the one holding him up as the non-believer. Prove it.
You stated “The error is that Eddie Van Halen wasn’t a believer..” what the heck dude? I asked you how do you know as the article YOU posted says nothing.
Prove he was.
Why is it OK to assume someone is a believer and yet not OK to assume someone is an unbeliever?
Jesus said.....
Matthew 7:13-14 “Enter by the narrow gate. For the gate is wide and the way is easy that leads to destruction, and those who enter by it are many. For the gate is narrow and the way is hard that leads to life, and those who find it are few.
So statistically speaking, you'd be more likely to be correct that a person isn't a believer, than one is.
Additionally, we are to confess that we are.
If someone does not profess to be Christian, there is no valid reason to assume they are. Other than you just want to sound like a nice person by not assuming that they weren't.
But that doesn't change anything about where they really are. It's a kind of Christian virtue signalling.