Many....many...men/women, happily married, reasonably sane, have, are, and will continue to commit adultery....why do you think God made that Commandment part of the ten????!!!!who="Oxbow"
Most reasonably sane people understand, when you use a condom, if for the protection against any type of VD, HIV, the flu, ingrown toenails, it also prevents pregnancies...which is the act of birth control!!!!
It does not have a dial with settings for only VD HIV flu ingrown toenails protection, as well as, for only birth control.
Analogue: When you fire a 12 gauge shotgun loaded with buckshot into the head of a person, he is dead as a door nail...don't matter if you only intended to scare him!!!!
'Reasonably sane people' don't have to be protected against ANY type of sexually transmitted disease.
One man/one woman marriage is not troubled by STD's. "Thou shalt not commit adultery", is a great STD preventative.
By your logic, God wasted His time making that Commandment one of the ten...
If ever you come out of that heavy fog, you might be able to see the error in your thinking....