Why is artificial birth control such a terrible sin?
For the same reason that abortion is such a terrible sin. Others may elaborate.
Hi. This short essay may answer your question (RCC view): Www.catholic.com/tracts/birth-control. It is one of those things that the Catholic Church has preserved in its teachings while the Protestant community has largely departed from it in the last half- century or so. See what you think. Best regards, fhc.
Artificial birth control reduces the marital act to a selfish sterile event that intentionally removes the life giving power of God from the center of the relationship.
In a larger social context, it is hypocritical to enable sterile fornication, while condeming homosexual acts. Both are united in their sterility and refusal to create life.
I say this as a great sinner who likely has you beaten in needing God’s foregiveness.