why do we as Catholics believe that using artificial contraception is wrong?

I was out of the monastery yesterday.

Whenever I go to town, my structured routine for the day gets messed up and so, the next day surely becomes a hectic day for me. Town trips of monks always distort their schedule for the day and the monk concerned should make it up the next day and take things up where he left. That's what life is like in the Cloister.

As for me, to compensate for the whole day's absence from the giftshop, I needed to take a little time from my freetime in the afternoon to be able to cover the work that I missed the day that I was out. Anyways, before going back home yesterday, I decided to drop by my friend's place in Espanyola which was just in the way back to the monastery. He was very glad to see me parking my Nissan Xterra on his yard. He offered me a cup of coffee but I politely declined and instead, I asked for a cup of tea.

We had a very fruitful conversation about the issues that concerned the involvement of the Philippine Church in politics and the what-has-been things in the country's present setup.
Suddenly, I blurted out to him: "Hey Dan, how's Amy? Is she on the family way now?" Dan quicly replied saying, "Not yet brother, we haven't thought of having a child yet and my wife's using contraceptives."
Then he asked me if what he and his wife's decision to use artificial contraception does not violate the Church's teaching.

I explained to him over a cup of hot bigelow peppermint tea which he prepared for me, that as Catholics, they must be aware and should abide by the constant teaching of the Catholic Church on its prohibition of the use of artificial contraception.

This prohibition was taught by all major Christian groups until the year 1930. The Biblical basis for this is seen clearly in the sin of Onan in Genesis 38: 9-10 that says: "Onan knew that the descendants would not be counted as his, so whenever he had sexual relations with his brother's widow, he wasted his seed on the ground, to avoid contributing offspring for his brother. What he did greatly offended God, and the Lord took his life, too."

To contracept is to willfully exclude the possibility of conception and to "tie God's hands" so to speak. It is considered a violation of natural law. Natural family planning, on the other hand, respects the natural order of things, especially when couples abstain during fertile periods for various significant reasons. Spacing of children or limiting of children for serious reasons are permitted according to Pope Paul VI's 1968 encyclical "Humane Vitae" and Catholic Moral Teaching.

Every marital sexual act must be open to possible conception. The frequent Biblical allusion to the blessings of many children mitigates against the "contraceptive mentality." One might draw an analogy to eating, which involves both nutrition (its primary function and purpose) and pleasure. If a person eats for one reason only, and not both, it is considered strange and unnatural.

Have a blessed fourth week of Lent to all of you!