And thus keeping the commandments of God is a privilege, not a chore. Sure, they believe they have God's grace through Jesus, so if they start attending a Messianic synagogue, it's not because they think they have to in order to be saved. We live in a multi-cultural, pluralistic society unlike any since the cosmopolitan era of ancient Rome. We cannot help anymore being aware of each other's religions, and that fact alone makes it very difficult to insist that you or I have the true religion, that our neighbor of another faith is a benighted heathen. Religious belief tends to become diluted in a society like ours.
Beliefs start rubbing off on one another.
I know others who are ostensibly Christians in dialogue with Jews and who have given up their belief in Jesus as the messiah. I knew a Pentecostal Christian who devoted himself to keeping all the laws of Judaism. Unitarian churches are filled with mixed-faith couples whose children receive a Comparative Religion course as their catechism. Groups like the Amish and the Hasid communities of Brooklyn are only exceptions that prove the rule. They have erected their walls so high precisely because they see the danger of pluralism and assimilation looming so largely.