Time out.
I guess I'm one pro-lifer who's not a member of "you guys". Spermicide does not destroy an embreyo, it helps prevent conception. Bluntly it reduces the chance of a live sperm reaching any fertile egg that may be present. It's not fail-safe, does not destroy the egg, and does not harm an embreyo that is already implanted.
So, explain how reducing the chance of conception is destroying an already-existing life; a.k.a. murder?
There have been plenty of medical cases where a spermicide has killed a fertilized egg - after conception, but that isn't your argument.
Before conception: The "you guys" that I belong to believes that intercourse is a three-way bond between the man, woman and God. Intercourse should never be entertained by removing God from the equation. Allowing God into the bond, allows God to dictate whether a life will be created or not.
Birth control is an in-your-face slammed door to God; hence prohibiting a life that He may have intended from being born. We look upon that as the worst of sins. Denying life = murder.
I have no heartburn with people who do not hold these beliefs using birth control. We have a forgiving God. He said: "Forgive them for they know not what they do." It doesn't change the wrongness of the act.