[Assialibabar]

I am 23 years old and there is a boy who is the same age as me.. me and him would like to get married.I have told my mum about him but she doesn't agree.. because he is not the same cast as me.. I am sunni and he is ahmadi.we don't have the same beliefes and for that reason my mum isn't allowing us to get married, she thinks that these people are none believes and not muslim.. is it true? Is is wrong for me to marry him?