Baptism is Necessary for salvation
Irenaeus (120? - 200), “'And dipped himself,' says [the Scripture], 'seven times in Jordan.' It was not for nothing that Naaman of old, when suffering from leprosy, was purified upon his being baptized, but it 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 new-born 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).
Origen (185 - 254), "The Church received from the Apostles the tradition of giving Baptism even to infants. For the Apostles, to whom were committed the secrets of divine mysteries, knew that there is in everyone the innate stains of sins, which must be washed away through water and the Spirit." (Origen, Commentary on Romans, 5:9)
Tertullian (155 - 220), “When, however, the prescript is laid down that 'without baptism, salvation is attainable by none" (chiefly on the ground of that declaration of the Lord, who says, "Unless one be born of water, he hath not life.'" (On Baptism, 12:1, A.D. 203).
Ambrose (340? - 397), “The Church was redeemed at the price of Christ's blood. Jew or Greek, it makes no difference; but if he has believed, he must circumcise himself from his sins [in baptism (Col. 2:11-12)] so that he can be saved…for no one ascends into the kingdom of heaven except through the sacrament of baptism...."Unless a man be born again of water and the Holy Spirit, he cannot enter the kingdom of God" (On Abraham 2:11:79-84).
Baptism is Not Necessary
Clement of Rome (? - 110), “And we, too, being called by His will in Christ Jesus, are not justified by ourselves, nor by our own wisdom, or understanding, or godliness, or works which we have wrought in holiness of heart; but by that faith through which, from the beginning, Almighty God has justified all men; to whom be glory for ever and ever. Amen." (The First Epistle of Clement to the Corinthians, Chapter 32).
Polycarp (69 - 150), "by grace ye are saved, not of works,' but by the will of God through Jesus Christ....If we please Him in this present world, we shall receive also the future world, according as He has promised to us that He will raise us again from the dead, and that if we live worthily of Him, 'we shall also reign together with Him,' provided only we believe…” (Epistle to the Philippians, 1, 5, 8)
Marius Victorinus (280 - ?): Every mystery which is enacted by our Lord Jesus Christ asks only for faith. The mystery was enacted at that time for our sake and aimed at our resurrection and liberation, should we have faith in the mystery of Christ and in Christ. For the patriarchs prefigured and foretold that man would be justified from faith. Therefore, just as it was reckoned as righteousness to Abraham that he had faith, so we too, if we have faith in Christ and every mystery of his, will be sons of Abraham. Our whole life will be accounted as righteous. Epistle to the Galatians, 1.3.7. Mark J. Edwards, ed., Ancient Christian Commentary on Scripture, New Testament VI: Galatians, Ephesians, Philippians (Downers Grove: InterVarsity Press, 1998), p. 39).