You read the Bible straightforwardly. It teaches we are justified by faith and you believe that. You have no problem understanding that faith is expressed in response to what God has said. As Abraham following what God had told him to do, proceeded to offer his son Isaac. God had not revealed to him further particulars, so he went on the information he had. The Bible thus says that in so responding, the scripture was fulfilled which says, "And Abraham believed God and it was reckoned unto him for righteousness" (James 2:23). Without such action his faith would have been dead and ineffectual James 2:22, 26). You thus have no problem understanding the necessity of repenting, confessing, and being baptized in order to be saved by faith. About baptism, the Bible straightforwardly says, "Baptism saves you" (1 Pet. 3:21).

You are also aware that because of certain systematic theologies devised and organized according to human fancies, there are people who cannot read the Bible in that same way. They struggle mightily to offset what the text clearly says. They devise schemes to explain baptism in ways the Bible does not. For instance, they say that baptism is just a sign of salvation, of a covenant of justification you already have. The Bible nowhere says that. The commentary notes in some NIV editions, and the Ryrie Bible, struggle to make baptism only symbolic in Romans 6:3-7, contrary to what the text clearly says. There is really an all out assault today against the necessity of baptism. These efforts will mislead many, but the open discussion generated will only be helpful. Truth has nothing to fear from that. But we must be ready with the truth whenever and wherever these unscriptural ideas arise.

There is a popular radio preacher name Hank Hannegraff who has a website wherein he tries to explain away what each passage on baptism says. Below is a copy of what he says on 1 Peter 3:21. I have highlighted portions of his own statement which make his conclusion untenable:

"The wording of 3:21 may seem to support baptismal regeneration, but a careful look at the parallels by Peter, and the Greek syntax, reveals that his typological comparison points in another direction...The first word in this verse is the neuter pronoun translated "which," referring back to "water," a neuter noun, not to "ark," which is a feminine noun. Wuest translates it, "which (water) as a counterpart now saves you, (namely) baptism." Thus, the water of Noah's day is a type of the water of baptism. Note the New Jerusalem Bible: "It is the baptism corresponding to this water which saves you now — not the washing off of physical dirt but the pledge of a good conscience given to God through the resurrection of Jesus Christ." The ark would more accurately refer to salvation, since the ark delivered Noah and his family as it was lifted by the flood waters, but ‘[Peter] was centering upon the issue of water in order to use baptism as an analogy to Noah's deliverance through the suffering and judgment of his day'."  

The highlighted portions above are clearly what the passage says, but because they did not make sense to Hannegraff, or that the ark would seem a better comparison, he just casts aside what the words plainly say. He is right about modifier and antecedent, which then says the water of the flood prefigures baptism saving us. That does not in any way get away from the fact that the passage still says, "Baptism saves us." If Hannegraff never understands the comparison, just let him believe the words, "Baptism saves us." He did not deal with the meaning of the words. What the waters of the flood did for Noah, because of his faith in building the ark (Heb. 11:7), was to lift him up and separate him from the sins of the defiled earth and consequent judgment. The water separated Noah from the sins of his age, and consequent destruction: The like figure whereunto baptism now saves us.

For instance Baptism is for the remission or forgiveness of sins (Acts 2:38). Baptism is where by the blood of Christ sins are washed away (Acts 22:16). After baptism we arise to walk in newness of life (Rom. 6:4). Our sins are cut away from us being buried in baptism (Col. 2:11-12). In baptism we are separated from sin.

Hannegraff wants to make baptism only symbolic. He says baptism is only an analogy to Noah's deliverance through the suffering and judgment of his day. So baptism represents suffering? He is making it up. What an insufficient struggle to escape what the Bible plainly says. His own quoted authorities say the flood waters are a counterpart to the water of baptism which now saves us. The waters of the flood did for Noah what baptism does for us, separates us from sin and destruction. Therefore baptism (preceded by faith and repentance Mk. 16:16; Acts 2:38), separates us from sin. It saves us.