A simple answer to why artificial contraception is wrong

Artificial contraceptives take away from the authority of God that is his alone. Only He can choose when whether sex leads to procreation. That is one of the two ends of sex (the other unity). Killing is another example of taking away God's authority, but it has it's own motivations of hate, anger, and cause of pain to loved ones. Artificial contraception has motivations such as selfishness and greed.