The following is an excerpt from article DB040 from the Christian Research Journal by Hank Hanegraaff. The full PDF can be found by following the link below the excerpt.
The thief on the cross provides perhaps the most potent proof that we are saved by faith or belief and not by baptism (or any other work). When this thief placed his faith in Christ on the cross, Jesus said to him, “today you will be with me in paradise” (Luke 23:43). In his case there was neither the necessity nor the opportunity for baptism.4 Baptism would have symbolized his entrance into a community of believers on earth. The cleansing power of Christ’s blood to which baptism points, however, was sufficient to assure him of his entrance into a community of believers in eternity.
The Book of Titus provides additional compelling evidence against baptism being a condition for salvation. Paul made it clear that “rebirth and renewal” are not the result of “righteous things we had done,” but rather “because of his mercy” (Titus 3:5). The “washing of rebirth” is not literal water baptism, but the cleansing of the Holy Spirit that “washes” away our sins by the blood of Jesus Christ (1 Pet. 1:18-19: 1 John 1:7; Rev. 1:5).
Christ’s words in Mark 16:16 clearly indicate that belief, not baptism, is the condition for salvation.5 Here Christ said, “Whoever believes and is baptized will be saved, but whoever does not believe will be condemned.” It is clear from the first part of His statement that baptism should follow belief. It is equally clear from the second part, however, that belief alone, not baptism, is required for salvation. Christ did not say, “Whoever believes and is not baptized will be condemned.” Rather Christ makes nonbelief (with or without baptism) the only condition for condemnation.