But He doesn't. As intelligent and supreme as He supposedly is, He doesn't show himself, like Jesus supposedly did years ago. So does He or does He not want to communicate with us? Why wait until we die for the 'ultimate test'? It's like "I won't show myself or give you proof of my existence, but you have to trust me on this. I'm here..... and if you don't believe that, you're doomed!"
He gives us such a wonderful rational brain but then demands that we not be rational? i.e. question Him and His existence? Because that would doom us?
"why the Abrahamic God is the most rational and probable ultimate being" - You describe Him like you know him personally. You only know Him by how others (and the Bible) describe Him...think about that.....