The thing is, God can give you 20, 25 kids. I don't want 25 kids. Is that wrong? If you actually knew that it was the will of God to have more kids, and you chose not to anyway, then I suppose that would be wrong. I really like the saying that Maximilian Kolbe used to say. The equation for holiness is w = W. The small w represents my will, and the large one God's will. If my will equals God's will, then I will be holy. Since God created us to be holy, (and in the end we will become holy, if a little purgatory is required) then anything that puts my will before God's will is a sin... so if God wants you to have lots of kids, or be a nun, or be poor, or be a high powered lawyer who fights for justice.... whatever God wants, we seek His will, even if it means having 25 kids.
But I don't think God wants us to have 25 kids. Our attitude has to be that every kid is a gift- because of course each one is. But when you get married (the primary purpose of which is to build a family, and companionship is secondary) you are entering into a covenant with God. One of your vows is to be open to life. "Do you promise to receive children lovingly from the Lord?" "I do."
So it's like you enter into a bargain with God where he says "I'm going to put you in charge of growing a garden, here's a plot of land and the tools and the seed, I'll provide the rain and the sun, you take care of it." The attitude of contraception is like saying "gardens are a lot of work, I'd really rather not grow one. So I just won't plant the seeds" or worse "I will plant these seeds, but then I will spray round up on my garden so nothing will grow." The reason God gave you the plot of land is because he had a job for you!
On the other hand, if you just plant seeds all over the place, or in the wrong season, your garden can become over grown. So you do want to plan. I always hoped to have a large family, but now at three kids my wife's health is suffering. It is likely that we will have to stop at 3. But contraception is out, so we'll have to use NFP.
NFP stands for 'natural family planning.' Contrary to popular belief, this is not the rhythm method which assumes that every woman is on a 28 day cycle and so you just have sex when the woman is infertile, which you judge based on when she gets her period. It is true that a woman is only fertile for a few days of the month, but not true that every woman is on such a regular cycle. So there are much more sophisticated ways for knowing when a woman is fertile. I won't get into them here, and anyway I am hardly an expert, but suffice it to say that NFP takes into account the woman’s natural cycle, respects her body, and yes, abstains from sex when she is fertile if you are trying to avoid having kids for good reasons.
As to the comment that as a woman you have more to offer the world than simply making and having children- this is true, but we have to be careful not to act as though making and having children is some small thing! My vocation as a father should be prioritized like this- God, Wife, Kids, work (which in my case is ministry.) Anytime I put these in a different order my life becomes ‘disordered’.
GK Chesterton wrote in the 1st half of the last century, and he described what would happen if Contraception became widely accepted. (He lived in England, and the Anglican Church reversed its stance on contraception in the 1930’s.) The attitude of contraception would lead to seeing children as a negative consequence of sex, and ultimately to abortion. It would also remove the commitment that sex entailed, leading to casual sex, higher adultery rates, higher divorce rates, the use of sex for pleasure, men using women more, and ironically with that culture shift would come an increase in unwanted pregnancies, single mothers, the breakdown of the family, and seeing as the family is the building block of society, eventually the breakdown of society. It is interesting how many of the things he predicted came true! And I don’t think he even recognized how with all this would be the rise of pornography, (certainly he could not have predicted the internet as a means), the rise of Sexually Transmitted Infections, homosexuality, prostitution, human trafficking for the sake of prostitution (biggest form of slavery in the world today)…. Etc.
I think it would be over stating things to blame all of these social ills on contraception- however contraception is one of the symptoms of a “Culture of Death”, as JPII called it. As stated before, reducing Catholic ethics to a list of rules misses the point entirely. This is about an attitude, and a philosophy of life. The proper Catholic attitude is that Sex is good and beautiful, even Holy, because it is through Sex that a man gives himself to a woman, and she receives him, and a new human life comes into the world. The sacredness of this act is so profound that it is a part of the sacrament of Marriage.
To the reader who is interested in learning more, I recommend you research John Paul II’s Theology of theBody. Or if you are between 14 and 18, attend the Spring Retreat at Our Lady of Victory Camp, May 3-5 2013, where we will be diving into these teachings in depth!