What guts do you think it needs to claim that the only God is talking only to you and everyone needs to believe in your claims or face eternal hellfire? We can find many such gutsy people in history. Nowadays, we put them in mental asylums.
What is the harm in allowing people to decide for themselves who is God and whom to worship? But your great religion and its wonderful God are extremely afraid of other gods. You God throws a tantrum when other gods are worshipped, like a spoilt child does when you buy a toy for his brother or sister. Like a mafia boss, he loves those who praise him, but makes threats to those who are infidels(rival gang) or apostates(left his gang)!
