I'm not sure how religion and life-long love necessarily fit together. I am Buddhist, my husband is Protestant. We are completely accepting of each other's differences, and we also have many things in common.
As far as a marriage relationship that lasts through a lifetime, I think it has a lot to do with commitment and open-mindedness. Commitment to each other and to keeping the relationship working, and open-mindedness to change and compromise. As a relevant example, I was Christian when we were first married, but over the years became disillusioned with various organized religions. As I pondered on that disillusionment, I found that I had difficulty understanding the belief in any kind of deity. I studied different religions and then found that Buddhism fits with my world view. (Buddhism is actually a philosophy, not a religion.)
My husband could not completely understand my change in view, but he is totally accepting of it, as I am totally accepting of his religious preference.
One of the things that makes us human is our capacity to think these deeper thoughts!