In Romans 4:11, Paul says that circumcision was the sign or seal of the righteousness which Abraham had by faith. Thus, Abraham was justified by the faith he had before he was circumcised.
So far so good. Just don’t put in the word “alone” after faith above. Many people do that (I am not saying this of you). And it throws them off.
You went on . . . .
But if baptism is the ‘Christian circumcision’, why is justification linked to baptism?
Because “Baptism” and “faith” are always linked together. Baptism cannot be reduced to a mere water ceremony (if it were, it would not be “baptism”).
There is a natural faith or “belief” if you will, that you take to your baptism. Then there is the supernatural saving “faith” we receive in Baptism (which is one of the special “supernatural” Graces we receive at Baptism).
(If you want I can expound on these concepts from Scripture and the Catechism. Let me know if you want more information on this concept though as I don’t want to over do it with information here)
Wouldn’t this mean that faith is what justifies and baptism is the sign and seal of the ‘righteousness one has by faith’?
No because as I mentioned, “faith” and “Baptism” are always together. They are inextricably linked.
The circumcision of the flesh could never save us. We need to put on the “circumcision of Christ” . . . . we need to (by the Grace of God) put on “Baptism”.
In Romans 3
St. Paul in part of Romans, was addressing Jewish people in Rome who thought “works of the law” could save them. St. Paul specifically mentions “circumcision” in this context and contrasts Jews (circumcised) and Gentiles (uncircumcised) in Romans 3.
St. Paul’s point immediately afterwards (in Romans 4) was Abraham was in some sense justified BEFORE he was ever circumcised. St. Paul is basically reminding them . . .
. . . . “So you see “works of the law” such as “circumcision” didn’t save Abraham, so why would you think “works of the law” such as “circumcision” could save you?”
St. Paul’s point in Romans 4, would be . . .
Therefore you Jewish persons who think you do not need to be concerned with faith in Christ . . . . because after all, we are “circumcised” . . . need to rethink that theology.
That’s all that St. Paul is saying in Romans 4. St. Paul is not teaching justification by faith alone here (or anywhere else).
Hope this helps.