I don't understand how contraception equals a mocking of God.
That seems like a real exaggeration to me.
Killing a person is intrinsically evil, and yet we have the Doctrine of Just War. We are not considered to be in a state of mortal sin if we kill someone in self defense.
but if we contracept to prevent illness, death of the mother, death of the baby....mortal sin - no exceptions.
Actually, murder is intrinsically evil. Killing a person is not, for the reasons you laid out.
Once again, I go back to our being made in the image and likeness of God, and that a spouses are called to love one another as God loves, that is, with a life giving love. To fail to love in that manner is the mockery, it demeans the love that God loves us with. Furthermore, it prevents to two from becoming one, wherin lies the beauty and sanctity of marriage.
And yes, contraception for any reason is intrinsically evil. However, postponing or avoiding pregnancy is not intrinsically evil. It's not the end achieved, it's the means of obtaining the end.