Because you are not clearly saying what "Believing in Him" actually looks like.
And I know why.
You can't.
Because Believing in Him means Obeying him in repentance from what one has done because of what one HAD believed.
The Gospel is not a message to Believe in Moses. To believe in Jesus means that one had needed to repent from what one DID (to obtain forgiveness) because of that belief in Moses. Jesus did not come preaching Believe in ME. He came preaching REPENT, (because that's what "Believing in Him" means.)
But your narrow narrative cannot abide this. So you're unable to explain what "Believing in Him" means beyond mere circular repetition.
You'll spin your wheels in these thoughts several times, and at some point I'll leave the dance knowing you cannot break free from the whirling dervish.
Rhema
In all, and with all due respect, you have it backwards. You preach that Repent means "Believe in Him" while in Truth, "Believing in Him" means REPENT !! If one does NOT Repent and Obey, one is not Believing in Him. If one does Repent and Obey, one can be said BY THOSE ACTIONS of Repentance and Obedience to be Believing in Him.
I'm not even sure you can understand my position, your mantra having been so dug in up in your brain. I, though, understand both, and right in this post explained what "Believing in Him" looks like. (And I've done so before.)
Thanks for the dance. You should Repent.