if you consider that the god they believe in:
- cannot be seen or heard and is only known in books written by writers we do not know nor do we have the original writings
- does not listen to prayers from believers for security, safety, health, survival, protection, rescue, food etc
- promises things that have not come true though had plenty of time to act on the promises
- does not provide what you need to live
- let's you suffer, struggle, work etc equal to non-believers, treated equally
.......
How does a believer look at his/her parents if they hide themselves, do not provide for you (shelter, food etc), make promises but never live up to these, does not provide what you need to live, treats you like anyone else but not as their child? Would you copy that behavior as best practice? If not, why believe in a god?