there is a difference between condemnation and pointing out that something is a sin.
In any case, I said it was my opinion because I figured saying it was a fact would just make people even more angry. But I see now that was a pointless effort at trying to avoid undue conflict.
And you say God is the judge He makes the rules, we are to live by His commandments yet you already admitted to not following the mitzvot. If we are going to talk about commandments, then I am right in saying birth control is a sin. God said to be fruitful and multiply, Rabbinic law says to fulfill this mitzvot, a couple must have 2 children. Furthermore, certain rabbinic laws say contraceptives are a violation of this mitzvot. (and, it seemed to me like the conversation spread from simple birth control anyhow since you were talking about couples who don't want children at all, in which case the mitzvah to be fruitful and multiply is obviously fully supported by scripture)
You may not agree with my reasoning, but it is reason enough for me to say birth control is a sin, and I am going to tell people it is a sin. People don't have to agree with me, but if they are willing to start a conversation about it they have to endure listening to my views. If one does not want to hear that birth control is a sin, one should stay out of a thread titled "birth control... thoughts?"