I don't understand why parents of kids who die so young or are born severely life limited carry on believing in God ?

I mean surely they are believing in someone who either doesn't do anything about such awful things .......so therefore is not everywhere for everyone all the time ...a fundamental belief in Christianity......or if he is everywhere all the time and all powerful then either he's a nasty git giving kids terminal illness or he's not worthy of all the attention as he's crap at his job