I can only assume that you believe the opposite. Can you elaborate?
Do you consider Hindu or Buddhist marriages valid before God?
If so, are there any religions you don't consider valid before God?
Are there any Christian sects you don't consider valid before God?
If you reply "no" to any of these questions, then should people belonging to those religions or sects you have negatively judged ever have sex, since they will never be "truly" married before God - even though they may have consecrated their lives and relationships to God in their own ways, and be surrounded by millions of other who have believed the same way for hundreds or thousands of years?
Or doesn't it matter whether the damned heathens rut, since they're all going to hell anyway?