Reasons why christians condemn adultery

Jesus extended the definition of adultery to include sexual relations between a married man and a woman other than his wife (Mark 10:11-12, Luke 16:18). Other New Testament teachings also understand it that way (1 Corinthians 6:15-16, 1 Corinthians 7:2 ).

Therefore, for Christians, adultery is the sin of a married man having sexual relations with anyone other than his wife or a married woman having sexual relations with anyone other than her husband.

Christians believe in Jesus and his teachings. Jesus condemned adultery which is why Christians condemn it as well.

Reason 1: it is against the 10 commandments.
2: it is considered disrespectful to both spouses.
3 it is morally wrong

Americans often speak of their country as one of several large regions.  these regions are cultural units rather than governmental units --  formed by history and geography and shaped by the economics, literature and folkways that all the parts of a region share. what makes one region different from another? a region's multicultural heritage as well as distinct demographic characteristics like age and occupation make regions different and special. within several regions, language is used differently and there are strong dialects. there are also differences in outlook and attitude based on geography.