And now why do you delay? Get up, and be baptised, and have your sins washed away, calling on his name. (Acts 22:16 NRSV).
This text is a commonly-cited passage in favour of baptismal regeneration; in this text, Paul, while recalling the words of Ananias to him, couples baptism with his sins being washed away (απολουω), showing that water baptism functions as the instrumental means thereof.
Commenting on this passage and its theology of baptism, the Lutheran scholar, RCH Lenski, wrote:
16) The question: καὶ νῦν τὶ μέλλεις; as in the classics (Liddell and Scott), means: “And now why delayest thou?” Ananias is now encouraging Paul on his own account. He tells him what to do. The two aorist imperatives are causative middles: “get thyself baptized and get thyself washed as to thy sins” (B.-D. 317; R. 808). The action expressed by the aorist participle, “calling on his name,” is either simultaneous with that of the aorist imperatives or immediately precedes it, the difference being merely formal. “The name” is Jesus in his revelation; and to call on this name involves faith (Rom. 10:13, 14). This is one of the cardinal passages on the saving power of baptism; see the others, 2:38 discussed at length; Luke 3:3; John 3:3, 5; Tit. 3:5; Eph. 5:26. What makes the present passage unmistakably clear is the second imperative. Why was it not enough to say, “Having arisen, let thyself be baptized, calling on his name”? Why was “and let thyself be washed as to thy sins” inserted if baptism and its water did not do this washing to remove the sins? The answer has yet to be given.
Was Paul to submit to a mere symbolic ceremony? What lay heavy on his conscience was the guilt of his enormous sin of persecuting the Messiah himself (v. 7). With its water that was sanctified by the Word baptism was to wash away all this guilt, all these sins. This washing away is the ἄφεσις of 2:38, and Luke 3:3, the “remission,” the “removal” of sins. To be sure, this washing away is “picturesque language” (R., W. P.); it is figurative, to speak more exactly, and is appropriate in that baptism has water in connection with the Word, Eph. 5:26. But with “picturesque language” R. means that “here baptism pictures the change that had already taken place,” i. e., that is all that baptism does. R. does not seem to see that he contradicts Ananias. Whereas Ananias says, “Let thyself actually be baptized” (aorist), “let thyself actually be washed of thy sins” (again aorist), R. changes the latter and substitutes, “Let a picture be made of the washing away of thy sins.” It may be interesting to enact a picture, but that is about all. As βάπτισαι = a real baptism and not the mere picture of one, so ὑπόλουσαι = a real washing and not the mere picture of one. (Lenski, R. C. H. (1961). The Interpretation of the Acts of the Apostles (pp. 909–910). Minneapolis, MN: Augsburg Publishing House)
