More than probably, your friend did not understand what it means by "justification by faith".

One verbose way of understanding "justification by faith": Under God's unilateral grace abundantly shown through Christ, each and every otherwise hopeless sinner who, by God-given faith, calls unto the name of the Lord and receives the free but costly salvation are declared acceptable (as if blameless and without sin) before God.

Any beneficience or good deeds, without exception, must proceed out of and affirm our dynamic saving faith, to the glory of God who is the source of all goodness.

Any self-righteous good deeds are apart from such saving faith, and without exception, must proceed out of highly questionable and ungodly desire for self-glorification. In this case, the hideous motive of self-glorification behind the self-righteous good deeds is ample evidence for the sinner to be convicted of their depravity disguised in good deeds! In other words, any such self-righteous piety not only fails to achieve salvation before God, but add more self-inflicted insults to the penalty of sin.

Thus, there is only one way to salvation: justification by faith. Any man in comtempt of this is actually despising God's costly salvation plan through Jesus Christ. Let his self-righteousness speak against him in the day of judgment.