VI. The present effect of Christ's passion is daily realized by Christians, especially in Holy Baptism
All therefore that the Son of God did and taught for the world's reconciliation, we not only know as a matter of past history, but appreciate in the power of its present effect. It is He Who, born of the Virgin Mother by the Holy Ghost, fertilizes His unpolluted Church with the same blessed Spirit, that by the birth of Baptism an innumerable multitude of sons may be born to God, of Whom it is said, “who were born not of blood, nor of the will of the flesh, nor of the will of man, but of God.”
It is He, in Whom the seed of Abraham is blessed by the adoption of the whole world, and the patriarch becomes the father of nations by the birth, through faith not flesh, of the sons of promise. It is He Who, without excluding any nation, makes one flock of holy sheep from every nation under heaven, and daily fulfils what He promised, saying, “Other sheep also I have which are not of this fold; them also I must bring, and they shall hear My voice, and there shall be one flock and one shepherd.”
For though to the blessed Peter first and foremost He says, “Feed My sheep;” yet the one Lord directs the charge of all the shepherds, and feeds those that come to the rock with such glad and well-watered pastures, that countless sheep are nourished by the richness of His love, and hesitate not to perish for the Shepherd's sake, even as the good Shepherd Himself was content to lay down His life for His sheep. It is He whose sufferings are shared not only by the martyrs' glorious courage, but also in the very act of regeneration by the faith of all the new-born.
For the renunciation of the devil and belief in God, the passing from the old state into newness of life, the casting off of the earthly image, and the putting on of the heavenly form— all this is a sort of dying and rising again, whereby he that is received by Christ and receives Christ is not the same after as he was before he came to the font, for the body of the regenerate becomes the flesh of the Crucified.
Source: Sermons (New Advent)