ok...it s a good question and plz let me clarify 1 thing b4 i do...muslims believe in god and call him Allah...If u are refering to the God of Jesus and Moses then we are talking about the same god...

next...If u ask why God cant prevent evil then I have a better question...ask yourself why were you created in the first place? am sure you believe there is a purpose for everything...

God created this whole universe for a purpose so asking why doesnt he prevent evil is like asking why dosnt God work on my behlaf? He sure can but he created us for a purpose...and we should abide

Muslims believe God created us all to test our believes...and he created heavens especially for that purpose...