Baptism does not save us. God saves us by grace through faith. But baptism is closely linked to that as a picture of it. In 1 Peter 3:21 we read: “Baptism, which corresponds to this (= the waters of the flood in Noah’s time), now saves you, not as a removal of dirt from the body but as an appeal to God for a good conscience, through the resurrection of Jesus Christ.”
This verse can easily lead to the thought that it is baptism that saves. However, there are two things that show that would be a misunderstanding. First, there is correspondence to the the flood in the time of Noah. The flood itself did not save Noah. On the contrary, the flood killed many people. Noah was only saved because he had the ark in the flood. In the same way, baptism does not save if it does not go together with faith.
Baptism: an outward sign
Second, Peter shows that baptism as an outward sign does not mean anything if it does not go together with an inner conviction. For not “removal of dirt from the body”, as happens when we take a bath, is what makes baptism effective, but “an appeal to God for a good conscience”. The exact meaning and correct translation of this phrase has been discussed a lot. But at least it is clear that it points towards a spiritual reality that goes together with baptism, and that it is not the ceremony itself that saves us.
The best way to understand the phrase “an appeal to God for a good conscience” (ESV), might be ‘an appeal (or strong desire) to receive a good conscience in relationship to God’. So baptism goes together with seeking God and depending on him to receive forgiveness of sins and therefore a clean conscience. At the end of the verse it is then emphasized that all of this is only possible “through the resurrection of Jesus Christ”. Only because He conquered death and now lives forevermore, we can receive new life in the power of the Holy Spirit.
Trust in Christ
Just like the readers of Peter’s letter, we are called to trust in the risen Christ to receive a new, clean life in which we are ready to obey Him. Baptism is a picture of that, and God’s guarantee to us that He wants to give that.