What are the Christian teachings on remarriage?
Christians look to the bible for advice. I found a passage about divorce. In the bible it says: Anyone who divorces his wife and marries another woman commits adultery against her. And if she divorces her husband and marries another man, she commits adultery. (St Mark 10:11-12)
This means that remarriage isn't allowed in the eyes of the Lord brought them together and nothing should part them. But at the beginning of creation God made them male and female. For this reason a man will leave his father and mother and be united to his wife, and the two become one flesh. So they are no longer two, but one. Therefore what God has joined together, let no man separate (St Mark 10:6-9)
When it says "let no man separate" it includes a judge or whoever is issuing a divorce. Therefore the Christian teachings on remarriage are that it would be adulterous to remarry making it a wrong thing.
Which Christian church wouldn't allow divorce and why?
Roman Catholic and Eastern Orthodox churches wouldn't allow divorce because to them nothing can separate the marriage of man and woman even the law so remarriage would be unjust.
What do Muslims think about divorce?
Divorce is permitted but doesn't occur very often because divorce is the most hateful legal thing in the sight of Allah. If the man and wife have problems an arbiter (problem sorter) from each of the couple's families will try to get them back together. If this scheme fails then they can divorce.