Charles Ellicott Commentary Acts 2:41

"They then that received his word were baptized: and there were added [unto them] in that day about three thousand souls." — Acts 2:41 (ASV)

They that gladly received his word were baptized.—This was, we must remember, no new emotion. Not four years had passed since there had been a similar eagerness to rush to the baptism of John. (See Notes on Matthew 3:5; Matthew 11:12.)

Three thousand souls.—The large number has been argued as making it probable that the baptism was by affusion, not immersion. On the other hand:

1. Immersion had clearly been practiced by John and was involved in the original meaning of the word. It is not likely that the rite would have been diminished from its full proportions at the very beginning.
2. The symbolic meaning of the act required immersion so that it might be clearly manifested, and Romans 6:4 and 1 Peter 3:21 seem almost necessarily to imply the more complete mode.

The swimming baths of Bethesda and Siloam (see Notes on John 5:7; John 9:7), or the so-called Fountain of the Virgin, near the Temple enclosure, or the bathing places within the Tower of Antony (Josephus, Wars, v. 5, § 8), may well have helped to make the process easy. The sequel shows:

1. That many converts were made from the Hellenistic Jews who were present at the Feast (Acts 6:1).
2. That few, if any, of the converts were of the ruling class (Acts 4:1).

It is obvious that some of these converts may have gone back to the cities from which they came and may have been the unknown founders of the Church at Damascus, or Alexandria, or Rome itself.