In our Lord's solemn prayer to His Father for His disciples at the Last Supper, He said: "Sanctify them, O Father, in truth: Thy word is truth." Now as to sanctify, or sanctification, is the whole purpose of our lives, our Lord is evidently at pains to impress on us the fact that without truth that is, without the word of God - we cannot hope to fulfil the object for which we were created. The revelation of God is absolutely necessary for the love of God, since sanctification or holiness means nothing more than that love. It is clear from the witness of the New Testament that the reason that lies at the back of all the Church's ordinances, sacraments, confraternities, etc., all the good works done to our neighbour, all the charity and self-denial in the world, is simply the love of God; for without this our sacrifices are vain and our prayers a hypocritical deceit: "Not he that saith to Me, Lord, Lord, but he that doth the will of My Father." "If I give my body to the torturers, and have not charity, it profiteth me nothing"; and Saint Paul goes very carefully through a whole list of good deeds, and points out the faultiness of each, except they be done from the motive of the love of God. Hence, since sanctification means the love of God, and since truth can come to us only through the illumination of faith, the prayer of our Lord must be interpreted in the sense of these words of the Council of Trent: "Perfect love is based on perfect faith."
Why should this be? The reason is quite simple. It is impossible to love properly unless we know properly. If we have not a true idea about God, we can never really love Him. The pagans and others have such distorted ideas of what God is like that it is impossible for them to know Him as He is in Himself. So again those, for example, who would give up their belief in Hell would have no doubt an idea of God as all-merciful, but not of Him as all-holy and all-just. Thus the God whom they would love would only be in reality a caricature of Him, not God as He is in Himself. It is just for this reason that the Church has been so particular, so fierce even as it seems, against sins of heresy; for false doctrine prevents people from really knowing God and, therefore, from really loving Him. Of course, in a certain sense it may be said that love helps us to know, so that unless we love people and have sympathy with them we can never understand them; and this is undoubtedly true, for love and knowledge act and react upon each other. But even so, it is always knowledge that precedes; and the knowledge that comes to us from their own revelation of themselves must itself tend to a better love of them. So of God, the more I listen to His voice, the more I learn of Him, the better I know Him, so much the more and the better will my love of Him be also. For Faith must precede Love.
Apart, therefore, from merely making acts of gratitude to God for giving me the faith, I have also to study, according to my ability, the truths of the Catholic religion; for the deeper my knowledge of Him, the more I must be drawn to love Him. The more clearly I can grasp His revelation of Himself, the more surely shall I be attracted by Him. He is so perfect, so infinite in His per fections, that truer knowledge of Him must end in truer love. It is as though I was in some darkened room and could see hardly anything at all; then gradually as my eyes get accustomed to the darkness, the outlines of things begin to loom out in vague, gigantic shadows; even details, at first obscure, after a while take on definite shape and stand out in clearer relief. So is it with the deep mysteries of God: they strike us as incomprehensible, as indeed they are; as contradictory, as indeed they are not - but by the sheer light of faith and fixity of gaze, the Divine Beauty becomes apparent, transparent, and eventually transfigures the world with splendour. I have no excuse for my ignorance, in this age of cheap and good Catholic books and pamphlets: I must, therefore, endeavour year by year to increase my knowledge of my religion, that my love of God may grow to the perfect stature of Christ.
- text taken from Meditations for Layfolk by Father Bede Jarrett, O.P.