You need to find a partner that is close to your beliefs. As a man, this is easier because it is easier to find a woman that is submissive and will be more likely to change slightly in ideology for her husband. You cannot have a marriage with different fundamental beliefs. You are tied together and working against each other will be detrimental to your relationship. This is actually a bible verse, but I interpret it to be more fundamental than what it reads as. It reads as dont marry outside the faith but this needs to be looked at in context. The context is hostilities between the Christians and their neighboring religions. The reason why you would not marry someone of the different tribe is that they may betray you and your people. People with different allegiances cannot marry. Today the best way to tell their allegiance is their ideology. A conservative, capitalist atheist is a much better friend to a capitalist southern baptist than a liberal catholic. I have seen so many marriages fall apart when the family is united in marriage but separated by ideology that I think ideology is way more important than religion. I have not seen nearly as many interfaith marriages fail when they are united in ideology. Typically, the interfaith couples will be much more sympathetic to each other’s religions and try to say that they say the same things, but the same faith couples separated by ideology will overlook their ideological differences and not see their differences in faith until it is too late. Then they will realize they are separated in ideology and in faith as they see their faith as being fundamentally different.
A leftist and a rightist will never be united. Leftists hate hierarchies and rightists acknowledge their existence, usefulness, and authority. You cannot unite these two.