There are many Protestants who say this. According to them, salvation comes when you profess faith in Jesus Christ and hand your life over to Him. Baptism is simply a symbolic gesture that shows the faith community that you have repented and committed yourself to Christ.
Catholics, however, have a stronger view of baptism. We believe that it is through baptism that God frees us from slavery to sin and makes us His children. This means that baptism is more than a symbolic gesture: it has true efficacy and power. Scripture clearly shows this:
Jn 3:5 Jesus answered, "Truly, truly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God.The difficulty, I think, is not so much in proving the power of baptism as it is in explaining how to reconcile these verses with the verses that say it is faith that saves.
Acts 2:38 And Peter said to them, "Repent, and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins; and you shall receive the gift of the Holy Spirit.
Acts 22:16 And now why do you wait? Rise and be baptized, and wash away your sins, calling on his name.
Rom 6:4 We were buried therefore with him by baptism into death, so that as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life.
Gal 3:27 For as many of you as were baptized into Christ have put on Christ.
Col 2:12 and you were buried with him in baptism, in which you were also raised with him through faith in the working of God, who raised him from the dead.
1 Pet 3:21 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 clear conscience, through the resurrection of Jesus Christ,
The best way to do this is to ask some questions: What is a saving faith? How does faith save? If faith is that single moment when you confessed that Jesus Christ was your personal Lord and Savior, then there is certainly no room for baptism. But, if you understand that faith requires from us a life-long "Yes" to Christ, then baptism is able to enter into the picture, since Baptism is one of the many actions that make up that life of faith.
The Book of Acts is filled with examples of faith compelling men to be baptized (cf. 8:12-13, 36; 10:47; 16:15, 31-33; 18:8; 19:2, 5). Jesus says, “He who believes and is baptized will be saved” (Mk 16:16). Baptism implies “faith in the working of God” (see Col 2:12 above). As the Catechism says, Baptism is “the sacrament of faith” (nos. 1236, 1253, 1992). Baptism and faith should not be pitted against each other. In fact, they go hand-in-hand.