The following comes from J.C. Kirby, Ephesians Baptism and Pentecost: An Inquiry into the Structure and Purpose of the Epistle to the Ephesians (London: SPCK, 1968) which affirm the salvific nature of water baptism (baptismal regeneration):
Eph 4:4-6
[T]he inclusion of baptism in this formula is an indication of its importance in the mind of our author, for in some ways it is the key word around which all the others are grouped. It is by one Spirit that we are baptized into one body (1 Cor. 12.13), it is at baptism that confession of faith in the Lord is made (Rom. 10.9), and it is the fact of our baptism which gives us the right to call God our Father. (Rom. 8.15: “we cry, ‘Abba! Father!’” is probably a reference to liturgical prayer, which could not be shared by the unbaptized.) The connection between baptism and unity is found in Galatians 3.27-28 and 1 Corinthians 12.12-13. (p. 151)
Eph 5:25-27
It has been argued that the phrase “having cleansed her y the washing of water with the word”, refers to a ceremonial bath taken by a bride before her marriage, but the majority of commentators hold that it refers to baptism, and that “the word” is either a baptismal formula pronounced over the candidate or a confession of faith made by him. In all probability the latter is the right interpretation, for there is no evidence in any of the early liturgies of a sacred form said by the minister of the sacrament while the candidate is immersed in the water. In Hippolytus, for example, the candidate is given a threefold interrogation: “Do you believe in God the Father Almighty? And in Jesus Christ . . . ? And in the Holy Spirit in the Holy Church?” To each of the questions he answers, “I believe”, and he is immersed after each answer.
In attempting to bring out the full meaning of baptism the author is not consistent in his use of imagery. Christ as the bridegroom administers the sacramental washing of baptism to the Church and at the same time acts as the one who presents the bride to her husband. The analogy breaks down towards the end of the passage (v. 32), for here Christ and the Church together constitute the new Adam, the bride has become the body.
The experience of the individual candidate in baptism is, in this passage, transferred to the life of the Church as a whole. She passed through death with Christ when he died on the cross for her (cf. 2.16), and the individual member’s baptism is an acceptance of that fact. It is also an eschatological fact. (pp. 151-52)
The References to “the seal of the Spirit”
“In him you also, who have heard the word of truth, the Gospel of your salvation, and have believed in him, were sealed with the promised Holy Spirit, which is the guarantee of our inheritance until we acquire possession of it, to the praise of his glory” (1.13-14). “Do not grieve the Holy Spirit, in whom you were sealed for the day of redemption (4.30). Though the word “baptism” does not occur here, both these passages must refer to baptism. The combination of “hearing”, “believing”, and “baptism” is a frequent one in Acts (8.12; 16.14-15; 18.8); in Ephesians, “sealing” takes the place of “baptism”, but that it means the same thing can be shown from the total context of the first passage; presumably therefore the second reference would carry the same meaning. The metaphor of sealing must have been a well-known one or more explanation of it would have been given.
The whole sentence from which the first passage comes is an expansion of one of the phrases found at the beginning of it: “Blessed be the God and Father of our Lord Jesus Christ, who has blessed us in Christ with every spiritual blessing” (I.3). These “spiritual blessings” are election (v. 4), sonship (v. 5), redemption (v. 7), knowledge (v. 9), the Spirit (v. 13), and the inheritance (v. 14). These blessings were all given to those addressed when they heard, believed, and were sealed Since the last three verbs are all aorists, they must refer to events at a definite point of time in the past. Now Paul uses the word “seal” of circumcision in Romans 4.11, where he says of Abraham that “he received circumcision as a sign or seal of the righteousness which he had by faith, while he was still uncircumcised”. Here he is using a Jewish metaphor, not coining one of his own. It is found in the berakah that was said at circumcision: “Blessed art though . . . who didst sanctify Isaac the well-beloved . . . and seal his offspring with the sign of the holy covenant.” From this Jewish usage the metaphor passed over into Christianity and was widely used as a synonym for baptism. Whether it was made to refer to the actual immersion itself or to an anointing which took place afterwards it is impossible to say, for the evidence can be read both ways. It could not have been a cross marked on the forehead with water, for the method of baptism would make this superfluous, but even if it were an anointing with oil, the metaphor is an inappropriate one, since no visible mark would be left. We do not know who was the first to use it, but it was probably Paul, for he refers to baptism as a kind of circumcision in Colossians 2.11; a simple extension of the metaphor would have led him to think of baptism as a sealing. The same metaphor is found in 2 Corinthians I.22, where it is used in an eschatological context and where the word “anointing” is also used. Since the word “anointing” is applied only to Christ in the rest of the New Testament, and in Acts 10.38 is definitely associated with his baptism, we may reasonably conclude that in the text of Corinthians Paul had baptism in mind. The association of the same ideas in Ephesians leads to the same conclusion. The second passage (4.30) is even more eschatological in tone. In the Spirit believers have been marked as God’s very own, so that they will be recognized as such on the day of the final deliverance. Again the aorist marks a definite point in the past, when the invisible presence of “the Holy Spirit of God”—we may note in passing the solemn liturgical phrasing—was given to the believer. (pp. 154-55)