I am a modern Pakistani Muslim girl living in The UK, almost my family live here, and all my immediate family is Muslim. However, there are a few people in my family who have married non-Muslims who have no intention of converting to Islam. One uncle of mine married a British Indian Sikh and now has two children with her (ages 12 and 9), they're raised with mixed religious viewings, and my grandfather's brother, who lives in Germany, is married to a white German Christian and has one daughter with her (age 34), his daughter is Christian.
Although this is the case, Inter-religious marriage is not talked about in my family, it's as if everyone's just accepted things as it is even though they all have hard views on Muslim-Muslim marriages.
I would like to know, what does it say in Islam about marriages like this? Is it haram or permissible and is wanting to marry a non-Muslim haram too (does the intention make you impure)?