Many phenomena might be described in that way, such as white and black people (especially in my region), healthy and sick, conservative and liberal, etc. etc. We're told that all of these divisions will be (are) scratched in Eternity, but meanwhile they serve as a convenient framework for thought and discourse.
The division of special interest here is that between conventional Christians and those I call enlightened ones. (Some might debate the legitimacy of such a distinction, and that's okay.)
How can these two groups get along? We know that Jesus said that "Brother will betray brother to death......, but that isn't always necessary. Paul said the faithful may redeem his/her spouse (cf 1st Corinthians 7:16).
We can learn! There are numberless marriages between Catholics and Christian of another stripe. They may become rancorous, but they don't have to, and probably rarely do. I know hundreds of people (including a son and his wife) who can make do quite satisfactorily with such an arrangement. It calls for tact, understanding, above all love.
Love "beareth all things, believeth all things, hopeth all things, endureth all things" (I Corinthians 13, the King Jim calls it charity.)
This love casts out fear and makes all things possible. Through the years it promotes understanding, tolerance, forgiveness, and finally the ability to live harmoniously and happily with a fundamental difference.
Happily I cannot say that I've experienced it, although it was a small factor in our marriage relationship, especially in the early years. Ellie, a college junior, had more or less given up the faith of her childhood. I had done that too, but 11 years earlier, and then I had been enlightened.
Throwing out the baby with the bathtub appropriately describes a vast number of ex-christians, ex-jews, you name it. A smaller group of fortunate people have learned how not to do that.
To adopt those facets of Christian theology that inform one's life with meaning, value, and purpose is everyone's aim. People have different levels of consciousness; no one has a corner on the truth. The path of Christ is to accept people where they are, pray for them, continuously try to understand them better and affirm what they believe as much as one can.
For some people a large order. Our hearts go out to those with relationships containing conflict. Prayer may well promote the solution.