The comments normally made outside the Catholic church about contraception make sense in Worldly Wisdom. But there are larger issues at stake here if we believe in an eternal, all good, all loving and all powerful God who allowed His Only Son to die on the Cross.
In His Eternity, He had the equivalent of a supermarket catalogue in which are the profiles of an infinite number of possible human beings. Out of that catalogue, He made the selection of exactly those whom He would endow with actual existence.
The generation of children does have an analogy with the Trinity. Out of the love between God the Father and the Son comes the Holy Spirit, who is the living love between them. The fruit of the love of a man and a woman (if God so chooses) is the eternal life of the child.
When a man and woman make love they are participating very directly indeed with the actions of God. Through their love, into the world can come one of the creatures (‘creature’ meaning ‘createe’ - someone who is created) whom God has predestined from all eternity to share eternal life and happiness with Him. A human being is made to have an animal body with an immortal spirit for the soul (the ‘soul’ by definition being ‘what gives life to the body’). The reproductive cells are guided by the laws of biology and by Divine Providence to generate the zygote, for which God creates an immortal spirit, immediately and out of nothing, that He has designed to be the perfect soul for that body (and that is why reincarnation does not happen - reincarnation downgrades the body to have no significance) and unites it with that body.
When a couple take the marriage vow, God has already decided exactly how many children He will send them, and the provision He will make for them.
Christ has told us that when a man and woman engage in the marriage act, they become in some mystical but real sense, ‘one’. ‘They are now not two, but one.’ ‘What God has joined together, man must not put asunder.’
What is wrong with divorce is that it ignores this reality.
What is wrong with fornication is that it takes the eternal power within our bodies and trivialises it by accepting the pleasure while rejecting the setting that God has established – and that for very good reason, because the primary end (or goal) of marriage is the procreation and raising of children, to fit them for eternal life in heaven.
What is wrong with contraception is that we are attempting to wrest from God Himself the eternal life that He has determined shall come into existence. We are saying in effect to God, ‘All right, I know that you created the world, and have decided how you are going to populate it… but – guess what! I’ve thought of a better way!’
In marriage and the begetting of children, the ordinary person who claims to believe in God is invited, in the most serious way, to put his money where his mouth is. We have not been promised there will be no hardships, but we have been promised that we will be helped along the way. Marriage is, for most people, the ‘normal means’ of Salvation.