Acts 8:34-36 (DRB) And the eunuch answering Philip, said: I beseech thee, of whom doth the prophet speak this? of himself, or of some other man? 35 Then Philip, opening his mouth, and beginning at this scripture, preached unto him Jesus. 36 And as they went on their way, they came to a certain water; and the eunuch said: See, here is water: what doth hinder me from being baptized?
Imagine the scene: some bigwig (v. 27) sitting calmly reading Isaiah in the cool of the day (v. 28), has Jesus preached to him (v. 35), and almost jumps out of his chariot at the first sign of water. This sounds like someone who believes that "baptism saves you," (1 Peter 3:21) not someone who believes baptism is a nice ceremony to have once you 'have been saved' (in the presence of family or friends, not alone with a stranger, for example).
Question: According to Protestants, why did the eunuch think his baptism was an urgent matter, after having the gospel preached to him, if baptism is not how one appropriates for himself ("puts on", Galatians 3:26-27) the Christ preached—not an intrinsic part of the gospel?
Cf. Mark 16:15-16; Acts 2:37-38; 8:12; 10:48; 22:16.
Thanks in advance.