Think. Noah and his family were not facing a crowd of people who were imminently trying to kill them and a giant wave of water came in to save them at the last moment. They were saved from that evil world by being removed from it. So it was the influence of evil that they were being saved from. They no longer had to remember that sinful world and they can now start again brand new. Just as when Christ cleanses our conscience of our past sins by being saved by God’s grace and we start brand new. 1 Peter 3:21 says that baptism saves us so to give an answer of having a good conscience.
Hebrews 9:14 says:
“How much more shall the blood of Christ, who through the eternal Spirit offered himself without spot to God, purge your conscience from dead works to serve the living God?”
You are first saved by God’s grace. THEN you serve the living God by being baptized (as a part of your service).
Our conscience is cleansed by the blood of Christ.
As for Acts 2:38:
First, it is important to understand that these were Jews (who rejected their Messiah) and not Gentiles. The Jews were supposed to know God’s ways and the Scriptures. So it was a call back to repentance for them in accepting their Messiah (as written in OT Scripture). Nowhere does Peter or any other apostle say these words for Gentile Christians. In fact, they did not know the Gentiles were included until Peter encountered Cornelius and the Spirit came upon him. But the point here is that the Jews were not learning about God for the first time. So this was not Initial Salvation but a call back to God. Second, if you wanted Acts 2:38 to apply to Gentiles (Which it is not), then this still does not really help you because the word “for” can be translated as “because” (Which is how the Amplified Bible translates it). In fact, the word, “for” can be defined as “because“ in definition 14 in the Webster’s 1828 dictionary (Which you can check out the link below).
For, King James Bible Dictionary
kingjamesbibledictionary.com
But if you are hard pressed to not accept this, one could understand that baptism is symbolic of Christ’s death according to Romans 6. So repentance (Seeking forgiveness with God) is what actually remits sin, and baptism is the symbolic picture of the remission of sins. So it’s a true statement. So the statement in Acts 2:38 is one part literal, and one part symbolic. So either way you slice it, you cannot use just one verse to support you here. We know Cornelius received the Spirit before being water baptized (Which proves one can be saved without water baptism).