Because everyone has the right to choose to believe as seems best to them. And you have the right not to believe. We all get to choose.

My beliefs make sense to me, and from my perspective it seems irrational to reject it out of hand. Seeing and hearing are not the only ways to know what is true. I have felt that God is real. It's much harder to share an inner feeling than to show something that you could look at and touch, and experience the same way that I do. Yes, I believe that God created this world and sent us here, and provides for us, often through other people as mediators, who respond to His promptings, ask what He wants them to do, or sometimes are not aware that they are serving God at all. But the purpose here is not to convince you to believe as I do - it is to try to explain that I have as much reason to believe as I do, as you do to believe (or not) as you do. Religion has been important to people since the beginning of this world. Anything important to someone enough has the potential to be used in hurtful ways. Why not eliminate money, land, oil, sex, ...? All of these have been associated with horrible acts of cruelty, because they are valued. Or, maybe we could all try harder to accept each other and treat each other as human beings with choices, and differences, and rights, and needs and values that may not always be exactly the same.

One of the kids that I work with recently decided to tell his family, who are very religious and had been encouraging him to follow the religion, that he is agnostic. I was impressed with this family because they listened to their son and allowed him his point of view, asking questions respectfully and not pressuring him or pushing him to change his mind. They exercised their belief in agency, or the right for all people to choose for themselves. It is a principle of this religion that God will never take away a person's agency and we should not either. This family has continued to support each other, listen to each other, and do their best to understand each other.