ANSWER:

If he made a mistake and apologized for it, this is sufficient and you don’t have to monitor him 24/7 as you are not the religious police and you are not his mother either! 

Few days ago a boy cursed Islam so I protested and told him that it was wrong. He said sorry but he didn’t regretted that so I stopped talking with him. Now can I play cricket if he plays too? And can I play with people who still talk and play with him after knowing that he cursed Islam (but they don’t think the thing he did was right)?? and what if he doesn’t play with us?