John Chrysostom
"[N]o one can enter into the kingdom of heaven except he be regenerated through water and the Spirit, and he who does not eat the flesh of the Lord and drink his blood is excluded from eternal life, and if all these things are accomplished only by means of those holy hands, I mean the hands of the priest, how will any one, without these, be able to escape the fire of hell, or to win those crowns which are reserved for the victorious? These [priests] truly are they who are entrusted with the pangs of spiritual travail and the birth which comes through baptism: by their means we put on Christ, and are buried with the Son of God, and become members of that blessed head [the Mystical Body of Christ]" (The Priesthood 3:5–6 [A.D. 387]).

Justin Martyr
"As many as are persuaded and believe that what we [Christians] teach and say is true, and undertake to be able to live accordingly, and instructed to pray and to entreat God with fasting, for the remission of their sins that are past, we pray and fast with them. Then they are brought by us where there is water and are regenerated in the same manner in which we were ourselves regenerated. For, in the name of God, the Father . . . and of our Savior Jesus Christ, and of the Holy Spirit [Matt. 28:19], they then receive the washing with water. For Christ also said, ‘Unless you are born again, you shall not enter into the kingdom of heaven’ [John 3:3]" (First Apology 61 [A.D. 151]).

Irenaeus
"‘And [Naaman] dipped himself . . . seven times in the Jordan’ [2 Kgs. 5:14]. It was not for nothing that Naaman of old, when suffering from leprosy, was purified upon his being baptized, but [this served] as an indication to us. For as we are lepers in sin, we are made clean, by means of the sacred water and the invocation of the Lord, from our old transgressions, being spiritually regenerated as newborn babes, even as the Lord has declared: ‘Except a man be born again through water and the Spirit, he shall not enter into the kingdom of heaven’" (Fragment 34 [A.D. 190]).
 
Tertullian
"[N]o one can attain salvation without baptism, especially in view of the declaration of the Lord, who says, ‘Unless a man shall be born of water, he shall not have life’" (Baptism 12:1 [A.D. 203]).    
Cyprian of Carthage
"[When] they receive also the baptism of the Church . . . then finally can they be fully sanctified and be the sons of God . . . since it is written, ‘Except a man be born again of water and of the Spirit, he cannot enter into the kingdom of God’" (Letters 71[72]:1 [A.D. 253]).
 
Council of Carthage VII
"And in the gospel our Lord Jesus Christ spoke with his divine voice, saying, ‘Except a man be born again of water and the Spirit, he cannot enter the kingdom of God.’ . . . Unless therefore they receive saving baptism in the Catholic Church, which is one, they cannot be saved, but will be condemned with the carnal in the judgment of the Lord Christ" (Seventh Carthage [A.D. 256]).