Well, I suppose that, if there was an elephant in your bedroom, you could deny that there was an elephant in there--but you'd have to give an alternate explanation of WHY the place is so damn crowded.
The decision to believe or not believe in God is the most interior one of our lives. God's not going to nudge the scales either way in the physical world, only in the realm of of the soul. And even that is going to be whisper-quiet