Romans 4:1-5 "What then shall we say that Abraham, our forefather according to the flesh, has found? For if Abraham was justified by works, he has something to boast about, but not before God. For what does the Scripture say? “ABRAHAM BELIEVED GOD, AND IT WAS CREDITED TO HIM AS RIGHTEOUSNESS.” Now to the one who works, his wage is not credited as a favor, but as what is due. But to the one who does not work, but believes in Him who justifies the ungodly, his faith is credited as righteousness"

A Roman Catholic response to Paul's argument for justification by faith in Romans 2 and 3 is that Paul is arguing against the Jewish or Mosaic Law as a means of justification, not against all forms of meritorious works (ie. sacraments).  They claim that this does not condemn the idea that faith and works are required for salvation (the Roman Catholic position).

However, in Romans 4, Paul uses the term "works" rather than "Law", and he also uses Abraham as an example of someone saved by faith alone, and Abraham pre-dates the Mosaic Law.  Abraham was not under the Law and he was also not circumcised when it was said “ABRAHAM BELIEVED GOD, AND IT WAS CREDITED TO HIM AS RIGHTEOUSNESS.” (Genesis 15:6)

Paul's argument is very thorough and clear in Romans, the law vs works vs sacraments "loop hole" just doesn't hold water.  If it was by works (in any way) it would not be of grace, but what is due/owed.  This is not how Biblical salvation is presented.  It is by faith so that it may be by grace!

"But to the one who does not work, but believes in Him who justifies the ungodly, his faith is credited as righteousness"