Well kiddo, Christians believe that marriage is a very special and important union between a man and a woman. They believe that God made humans to have companionship and love, and one way to show that love is by getting married.
In fact, the Bible says that marriage is so important that it even compares it to the relationship between Christ and the church. Christians believe that marriage is meant to be a lifelong commitment, and that the love and respect between a husband and wife should be as strong as possible.
Some Christians believe that marriage should only happen between two people who are committed to each other and share the same religious beliefs. This is why you may have heard of Christians only marrying other Christians. They believe that when they have this common ground, it makes their marriage stronger.
Overall, Christians view marriage as a sacred and beautiful thing. They believe that it should be taken very seriously and that those who get married should do everything in their power to make their relationship strong and loving.