I have noticed a difference among scholars of the biblical languages when it comes to translating 1 Peter 3:21 from the ancient Greek into modern English.
The New International Version reads, "...and this water symbolizes baptism that now saves you also--not the removal of dirt from the body but the pledge of a good conscience toward God. It saves you by the resurrection of Jesus Christ."
But the English Standard Version reads, "Baptism, which corresponds to this, 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."
I'm not an expert in biblical Greek, but from what I have read, the Greek word in dispute could legitimately be translated as either pledge or appeal. Perhaps it could be both a pledge and an appeal at the same time, since the Greek word seems to carry some degree of ambiguity. I'm not sure.
Whatever the case may be, both definitions provide some insight into what happens during a believer's baptism.
If the New International Version is correct, baptism is a pledge of a good conscience toward God. The believer is making a promise to follow Jesus Christ. He or she is saying, "I believe in Jesus. I understand my need for him. I accept him as my resurrected Lord. As such, I promise to follow him for the rest of eternity."
If the English Standard Version is correct, baptism is an appeal to God for a good conscience. The believer is asking for grace. He or she is saying, "I've messed up my life. I have sinned. I need your forgiveness, God. Please forgive me and show me grace because of what Christ has done to save me."
In reality, during baptism, the new believer is appealing to the grace of God while pledging to follow Christ. Neither definition excludes the other. Both work together in a God-honoring way.