Perhaps we should look at it as Jesus satisfying requirements which were a legacy of the 'Plant of Righteousness' or 'The True Vine' which had its roots in Abraham. Abraham had the beginnings of Law with circumcision. Then Law was added for his descendants including Jesus accirding to Jesus' biological nature. Jesus has died after a perfect life so He is now (resurrected) free from this Law. The rigteousness He has since then is Law-free. Being joined to Him joins anyone, Jew or not, to this new righteousness. It means it is of faith. Jesus is joined to God and is in complete faith to God. Joining oneself to Jesus is in faith too.
