That would be a bad definition, yes. But I will still argue that whenever I see people proselyting atheism because "big bang, stupid" and it is clear they have

That would be a bad definition, yes. But I will still argue that whenever I see people proselyting atheism because "big bang, stupid" and it is clear they haven't studied to much of neither physics or biology, then we have: * proselytizing * stronger belief than many Christians and Muslims and I will argue that they qualify as religious even if they don't have a deity.