The physical act of baptism is a work (obedience which follows salvation through faith is works) and we are not saved by works. (
Romans 4:5-6;
Ephesians 2:8,
9;
Titus 3:5 etc..).
Now in regard to Naaman, in the first place, if being healed from leprosy is an illustration of salvation, we have another case that reveals one can be saved without any water. Read it in (
Luke 5:12-15).
No water is found here.
Secondly, Naaman was
not even a believer until after dipping in Jordan. He said
"NOW" (after being healed) I know that there is no God in all the earth, but in Israel," (
2 Kings 5:15)
and vowed to worship only Him (vs. 17). If we follow this "example," we will have to baptize unbelievers! Naaman received cleansing from leprosy (not eternal life) after he dipped in the Jordan 7 times, but no sins were literally remitted for Naaman in Jordan. Likewise, water baptism does not literally remit sins.
The Bible uses the experience of Naaman as illustrative of the SOVEREIGNTY OF GOD, not of salvation by water baptism. Naaman was a heathen, not a believer, and did not know God until the miracle occurred. The purpose of the miracle had nothing to do with salvation by water baptism, but was to demonstrate "there is a prophet in Israel" (
2 Kings 5:8) and that "there is no God in all the earth, but in Israel," as Naaman found out (
2 Kings 5:15).