This subject always comes up as probably the most difficult of the Catholic Church's teachings to accept. I've mentioned this before, but since there's a lot of blogging of the anniversary of Pope Paul VI's HV, here is a quick reminder.
If you read and study either the Bible or the Qur'an, you will not find any orientation toward individual salvation. That's right... salvation is always described on a societal and community basis. SIN most certainly is discussed on an individual basis, as are the Gospels that relate the events and teachings in Jesus' life. Just to be clear, I am not saying that souls are not saved one at a time. But God's laws are not written with individual salvation in mind. God's laws are written so that the human species can survive and thrive as his children.
Therefore, God's "bar is raised higher" than the individual salvation, or sin, of any one person. God did not sit down and go, "Hmm, what is the list of things that all good individuals must do to be saved." God gave prohibitions and teachings to the "community of the faithful," starting with the chosen people, the Israelites. God's first words to Adam and Eve after they sinned regarded how humans as a whole would live, not just the sinners, or the obedient.
Birth control and homosexual behavior therefore fall under the category of God's admonitions for the survival and thriving as people as a whole. I described in a previous post that Biblical "gays" would never have dreamed of wanting a "gay lifestyle," for the most part, because individual sex acts and desires were by choice subordinated by the predominant desire of all men to have a wife and children. That's why there is condemnation of homosexuality in the Bible, but not a lot of stories or parables about individual sexual acts. God's not as concerned about individual sexual preferences but God is very concerned about how humanity and its society as a whole will, and there's no nice way to put it, will be allowed to continue.
So the Catholic Church continues to uphold the standard that God himself established for the community of the faithful (and humanity as a whole) to continue its well being. Those dogmas are the hardest to follow and God knows that, obviously. Therefore the Church cannot and should not "soften" or "modernize" its interpretation of the expectations by God of humans. However, when giving spiritual direction I advise that on an individual basis, these are the areas where one is most likely to be able to "take one's chances" with God.
God certainly understands family planning and spacing of births. Also, society has changed so that people are irresponsible toward supporting babies and single parents. So it is understandable, but not allowable dogma, that individuals make decisions about birth control and sex acts that are prohibited by God and his Church. If a person is leading a modest and virtuous life, but makes individual choices about birth control or individual sex acts, "I like your odds," if you know what I mean. Someone who "takes a chance" and is otherwise very pious and observant but practices artificial birth control in a family setting sure has "better odds" of being forgiven than someone who repeatedly aborts in order to be sexually promiscuous.
I have a headache from the terrible mood and violence of the times, and also the living conditions I've had to endure for years now, so I'm not going to go into detail on this subject. I mostly wanted to get it out there so you can start to think about how the Church is not supposed to "lower the bar" because it has a responsibility toward humanity as a whole to keep it right where God set it. However, there are certain sins that one can see that Jesus, for example, had a merciful view of, and thus one can understand being pious and yet "chancing it with God's mercy" in those areas. I think you get my point. Part of being judicious is keeping one's mouth shut and not high profiling those areas where you are "taking a chance with God's mercy." That way you do not tempt others to follow you in sin, when they may not be so well positioned in their internal virtue and morality. That's why I repeatedly admonish my gay friends to not "promote the lifestyle." Likewise I do not think that those on birth control should rub the priest's nose in it, or their parish, touting themselves as enlightened and modern. I think it should be confessed, obviously, but not advertised as an area where debate is valid, because it is not. God knows all and sets standards for humans for a reason. It is not a "report card" for one by one salvation, as many seem to think today. It is the conditions under which God will offer his protection for the continuation of humanity. Period.