Despite Paul’s insistence that our faith is modeled after Abraham, when he compares baptism to circumcision, we automatically adopt the attitude of the Pharisees:
“Unless you are circumcised according to the custom of Moses, you cannot be saved” (Acts 15:1).
“Unless you are baptized in the exact way we interpret it, you cannot be saved.” Some even apply this to those who would die on the way to the baptistery!
Instead, given Paul’s focus on Abraham, you would think we’d compare our baptism to Abraham’s circumcision:
““Is this blessing, then, pronounced only on the circumcised or also on the uncircumcised? We say, Faith was reckoned to Abraham as righteousness.” How then was it reckoned to him? Was it before or after he had been circumcised? It was not after but before he was circumcised. He received the sign of circumcision as a seal of the righteousness that he had by faith while he was still uncircumcised. The purpose was to make him the ancestor of all who believe without being circumcised and who thus have righteousness reckoned to them, and likewise the ancestor of the circumcised who are not only circumcised but follow the example of the faith that our ancestor Abraham had before he was circumcised.” (Romans 4:9-12)
This is not to deny the importance or even the “necessity” of baptism. Consider Abraham: had he refused the sign of circumcision, could one really say that he had a transformative faith?
Thus, circumcision was necessary, but that did not somehow cancel out the fact that he had already been justified by faith years before.
Baptism is necessary in that it is part of our identification with Christ and response to his gospel, which is how it saves, but that is not to say that one is somehow unsaved or not justified prior to their baptism.
Abraham was justified (saved) prior to his circumcision, but his circumcision was a confirmation of the justification he had received by faith and was therefore salvific. Had someone refused circumcision, they would have been cut off from the people (Gen 17:14).
Abraham is our example, not the Pharisees. Justification by faith prior to baptism doesn’t take away the importance or necessity of baptism. Baptism, like circumcision, is a sign or seal of the covenant we have with God on the basis of our faith in Christ, not the means by which we are justified.
Like Abraham, anyone who has a transformative faith will be baptized, even if their interpretation of baptism looks different than our own.