Yet, as we have seen, this obedience of faith is not the righteousness by means of which we are accepted by God. Obedient faith is the means by which we receive Christ's righteousness. Faith is the instrument by which righteousness is procured. Eating is necessary for the nourishment of our bodies, but it is the food we eat that actually nourishes us. Likewise, faith is necessary to receive righteousness but it is the righteousness of Christ which actually justifies us.
Faith is the only means for the receiving of justification.
Justification is not by faith plus the knowledge that one is among the elect of God. Justification is not by faith plus a certain amount of conviction of sin. True, none will believe unless they are the elect of God and are convicted of their sin and need of a Savior. But it is primarily our faith in God's promise of salvation in Christ for sinners which brings justification, not anything else we may know or feel. It is not sorrow for sin that unites us with Christ.