Apostolic Constitutions, Book VI 15

1Be likewise contented with one baptism alone, that which is into the death of the Lord; not that which is conferred by wicked heretics, but that which is conferred by unblameable priests, in the name of the Father, and of the Son, and of the Holy Ghost: and let not that which comes from the ungodly be received by you, nor let that which is done by the godly be disannulled by a second. For as there is one God, one Christ, and one Comforter, and one death of the Lord in the body, so let that baptism which is unto Him be but one. But those that receive polluted baptism from the ungodly will become partners in their opinions. For they are not priests. For God says to them: Because you have rejected knowledge, I will also reject you from the office of a priest to me. Nor indeed are those that are baptized by them initiated, but are polluted, not receiving the remission of sins, but the bond of impiety. And, besides, they that attempt to baptize those already initiated crucify the Lord afresh, slay Him a second time, laugh at divine and ridicule holy things, affront the Spirit, dishonour the sacred blood of Christ as common blood, are impious against Him that sent, Him that suffered, and Him that witnessed. Nay, he that, out of contempt, will not be baptized, shall be condemned as an unbeliever, and shall be reproached as ungrateful and foolish. For the Lord says: Unless a man be baptized of water and of the Spirit, he shall by no means enter into the kingdom of heaven. And again: He that believes and is baptized shall be saved; but he that believes not shall be damned. But he that says, When I am dying I will be baptized, lest I should sin and defile my baptism, is ignorant of God, and forgetful of his own nature. For do not delay to turn unto the Lord, for you know not what the next day will bring forth. Do you also baptize your infants, and bring them up in the nurture and admonition of God. For says He: Suffer the little children to come unto me, and forbid them not.