it is a sin because God intended for us to procreate, and sex is the gift of life. Using birth control is subrogating God's will, He is supposed to determine when life is created. As Catholics, we are called to be open to life (it is right there in the wedding vows too). Further, if you closely examine birth control methods, most of them other than the simple barriers or sterilization cause a spontaneous abortion after conception has occurred. We as Catholics believe life begins at conception, and that taking a life is a mortal sin.
IMHO, it is really really arrogant to tell the church to 'change with the times'. We are taught that the Church's rules are God's rules. Insisting on changing them is equivalent to telling God that you know better how to run things. God's law is God's law, we as humans are asked to follow it, not challenge it or pick and choose which parts we like and only follow those parts. One of the things that helped my faith grow is the recognition that despite all sorts of popular pressures, the Catholic teachings have remained substantially unchanged in 2000 years.
The church condones NFP as a birth control method since it does not interfere with God's intended function of the body. Numerous studies have shown that, when used properly (ie abstaining during the fertile periods), NFP is at least as effective as any other birth control method other than sterilization by removal of the testes or ovaries. It also does not have an on-going cost (pharmaceutical companies don't like it because they can't make a profit off of it), which makes it the ideal birth control. The caveat is that it is incumbent on the couple to develop self control to avoid sexual relations during their fertile time if they are not ready to accept a new life.
Annette, I'm sorry to hear that the behavior of people drove you from church. That is so not God's way.
