Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost. (Acts 2:38)
Those who quote Acts 2:38 invariably forget to quote Acts 3:19 which clarifies what is actually for the remission of sins: Repent ye therefore, and be converted, that your sins may be blotted out, when the times of refreshing shall come from the presence of the Lord;
And Peter was saying EXACTLY what he had been taught by the Lord: And that repentance and remission of sins should be preached in his name among all nations, beginning at Jerusalem. (Luke 24:47)
Water DOES NOT wash away sins. It is the blood of Christ alone that can wash away your sins. And that happens when a sinner repents and believes. Therefore Acts 2:38 does not mean that salvation is through water baptism. It simply means that salvation and baptism are almost simultaneous. And that is exactly what we see in the book of Acts.