I'm on my phone so apologies if this comes out muddled.
Firstly, I feel the need to say I class myself as spiritually agnostic. I don't believe in anything without proof but I can understand others have faith and am openminded about parts of various religions that seem feasible to me.
Secondly, if someone is questioning how people don't believe in God it is only fair that people can ask why someone does.
Now, disclaimers done, onto my point
Throughout history there have been many species that died out as the Earth's atmosphere changed and was no longer a good place for them to be. As humans, we have been lucky that all the changes have been ok for us and we've been able to adapt. IMO that is down to the random, not a creator.
In the Old Testament God seemed rather merciless to me and was something to be feared - if things weren't going his way he would wipe out the population and start afresh. Of course, that is just my interpretation of the Bible. I find it hard to swallow that when a bad thing happens to a good person it's 'taking one for the team' to make up for the bad things others do
I can't bring myself to follow that way of thinking which seems to born of organised religion.
When I look into my son's eyes I am amazed at how nature works and that two microscopic elements have turned into a person who has his own personality. I created that, I nurture it and make it grow. Not God.
There may once have been a higher power of some form (whether that is God, Gods, Mother Nature, aliens etc) but I don't believe they are here anymore. There are just some things that no loving 'God' would let happen to their creations.
Having said that, I understand how faith can bring peace to people and if it works for you that's great. I don't think those beliefs should be pushed onto others and I certainly don't want anyone pitying me for believing that my body has more to do with creating a child than any God