God out of His infinite goodness wills to lift us up to Himself in the measure that our weak nature allows, and for this purpose gives us a principle of supernatural life; a Godlike, vital principle, which is habitual grace. It is called created grace in contradistinction to uncreated grace, which is the indwelling itself of the Holy Spirit within us. Created grace makes us like unto God and unites us to Him in the closest manner: “this deification consists, in so far as is possible, in a certain resemblance to God and union with Him.” These two points of view we shall explain presently by giving the traditional definition and by determining precisely the nature of the union that grace produces between God and the soul.
It is on humble souls that God pours down His fullest light and grace. He teaches them what scholars cannot learn, and mysteries that the wisest cannot solve He can make plain to them.
—St. Vincent de Paul
Let us not fear to lose ourselves in this ineffable union with God. We are lost in an unfathomable abyss, an abyss, not of annihilation and darkness, but one of the greatest glory and happiness. We lose ourselves only to find ourselves again in God, or to find God Himself with His whole glory and beatitude. For the more we belong to God, the more He belongs to us; the more we live in Him and for Him, the more He lives in us and for us. Is a branch lost when it is grafted onto a more excellent tree and begins to receive its life from this superior tree? Left to itself, it would have a much less perfect life, but now it can boast not only of the life which it draws from the tree, but also of the life and perfection which the root and the trunk possess for themselves. Thus, when we are united to God by grace, we not only obtain and direct into our soul a ray of divine glory, a small stream of divine life, but we may also consider as our own the divine Sun Itself, the fountain of divine life, and we may rejoice at God’s perfections as though they were ours. Hence, by the very fact that we are deified in a twofold manner, we also partake in a twofold manner of the divine beatitude: first, by beholding the beauty and bliss of God as He Himself beholds and enjoys it; secondly, by possessing through grace this glory and bliss and calling it our own.
This article is taken from a chapter in Cultivating the Spiritual Life: The Beginnings of the Life of Grace & Mysticism as Told by the Saints, which is available from TAN Books.