It's not the first time I heard of contraception being a sin. Way back Theology classes on Morals and Sins, the issue was already discussed and had been cleared as far as the Catholic faith is concerned. The Church identifies SINS in accordance to the Holy Bible and on how they are based of erroneous and false MOTIVATIONS along with sin's adverse EFFECTS that ultimately harm any human being.
The Catholic Faith puts high value and respect for Human Life. Her rules and commandments set the very FUNDAMENTALS on the love of God, self and neighbors. This means anything that is unnatural which harms humanity is condemned.
Real Catholics believe in Family Planning and proper spacing of kids, and in a simple note if there's this desire of controlling birth, consistently one has to control and stay away of doing a thing that may cause that thing one avoids. In simple terms, if one has no intention of pregnancy then just refrain from sexual relations.
But then, this isn't what's happening with the modern society where many seems to fall an adherence and rather cling to devices which believe work as ceasing the natural body system and functions. And we all know that when anything normal is interfered with anything synthetic, they do produce side effects. Unfortunately with contraceptions, this doesn't stop at harming the person but these further do KILL the unborn.
Many would have believed as the Pharmas or contraception companies both advertise and market that artificial birth controls "prevent" but actually work later in the stages of human development which makes the supposedly "prevention" to "killing". Going back to the teachings and the Catholic dogma of giving value to human life, absolutely contraceptions are unacceptable.
Motivation wise, if there's this desire of not getting pregnant then there's no reason of doing acts that make this so. What is the difference of engaging in sexual activities when one knows she can be pregnant yet still do it, or do the act when one is definitely safe? Having the intention of not getting pregnant but still DO the act yet preventing it is different from having the intention of not getting pregnant and NOT DOING it.
Sexual intercourse is a LIFE GIVING ACTION. If a couple simply chooses not to have sex then they are not preventing any possible baby which is far different from a contracepting couple that takes the steps to contracept sexual intercourse. Choosing not to cause a baby and preventing a possible baby are never identical. This is where the motivation issue comes in and SIN is identified.
Finally, good readings can provide how people's mentality - contraceptive mentality to be specific is definitely an assault to genuine motivation. This has created major breakdowns in people's lives, families, society, and relationships. It is also to blame for murders on the youngest member of the human family. Awfully, a self-infested carnage on life's intangibles and priceless. These detrimental repercussions are of domino effects which aren't within reach as far as damaged control is concerned. It's not of losing hope, this just needs time to correct and recover.
Real birth control is self-control and this works well with the NATURAL value of discipline, sacrifice, responsibility and faith. Certainly, not the pills nor any other artificial devices.