This is what the Ecumenical Council of Trent says in its magisterial teaching-
Session 5
If any one asserts, that the prevarication of Adam injured himself alone, and not his posterity; and that the holiness and justice, received of God, which he lost, he lost for himself alone, and not for us also; or that he, being defiled by the sin of disobedience, has only transfused death, and pains of the body, into the whole human race, but not sin also, which is the death of the soul; let him be anathema:–whereas he contradicts the apostle who says; By one man sin entered into the world, and by sin death, and so death passed upon all men, in whom all have sinned.
If any one asserts, that this sin of Adam,–which in its origin is one, and being transfused into all by propogation, not by imitation, is in each one as his own, --is taken away either by the powers of human nature, or by any other remedy than the merit of the one mediator, our Lord Jesus Christ, who hath reconciled us to God in his own blood, made unto us justice, santification, and redemption; or if he denies that the said merit of Jesus Christ is applied, both to adults and to infants, by the sacrament of baptism rightly administered in the form of the church; let him be anathema: For there is no other name under heaven given to men, whereby we must be saved. Whence that voice; Behold the lamb of God behold him who taketh away the sins of the world; and that other; As many as have been baptized, have put on Christ.
If any one denies, that infants, newly born from their mothers’ wombs, even though they be sprung from baptized parents, are to be baptized; or says that they are baptized indeed for the remission of sins, but that they derive nothing of original sin from Adam, which has need of being expiated by the laver of regeneration for the obtaining life everlasting,–whence it follows as a consequence, that in them the form of baptism, for the remission of sins, is understood to be not true, but false, --let him be anathema. For that which the apostle has said, By one man sin entered into the world, and by sin death, and so death passed upon all men in whom all have sinned, is not to be understood otherwise than as the Catholic Church spread everywhere hath always understood it. For, by reason of this rule of faith, from a tradition of the apostles, even infants, who could not as yet commit any sin of themselves, are for this cause truly baptized for the remission of sins, that in them that may be cleansed away by regeneration, which they have contracted by generation. For, unless a man be born again of water and the Holy Ghost, he cannot enter into the kingdom of God.
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