Hello Trey
welcome to the forum
When I hear the Onan argument, sometimes I wonder... I believe what is being said about Onan is QUITE clear. In the old testament, it was expected of a man's brother to carry on his bloodline should he die before a child was concieved. The REASON Onan was withdrawing was because if he failed to impregnate his brother's wife, he would have to have sex again. Onan was abusing this situation with his brother's wife, using her for his own gain. This is a terrible sin. It was not the spilling of seed that earned him punishment, it was lust and taking advantage of his dead brother's wife's body.
Where are you getting that he did this as contraceptive rather than obeying his duty as a brother in law
Genesis 38:9 (New International Version)
New International Version (NIV)
Copyright © 1973, 1978, 1984 by International Bible Society
9 But Onan knew that the offspring would not be his; so whenever he lay with his brother's wife, he spilled his semen on the ground to keep from producing offspring for his brother.