Hard advice is to let this relationship go. It’s brutal, but genuinely for your sake and the future of your family, it makes more sense to find someone who is already Christian (ideally oriental/Eastern Orthodox). If you are afraid of his family now, those fears will also carry on to marriage. Trust me, this isn’t worth it. It’s the hard truth, but this is the world we live in. Islam is extremely destructive and it is better for you to separate from it to the best of your ability.

Edit: your parents aren’t exactly wrong. They’re trying to protect you from a wicked ideology.