Only one privilege is left open to a Jew for Jesus. He can at any time in life make teshuva. He can return in deep contrition to his heritage and to the God of his people. Some rabbinical authorities require a symbolic act. The returnee is required to confess his sins and repent of them before three rabbis.
Some authorities require ritual immersion in a mikveh.
They are not the kind of Jews we would want in our community. They are not the kind of Jews we would want our young Jewish people to marry. They are not Jews who speak for Israel and its religion. They are victims of Christian love. They are Jews who sold their birthright for a bowl of Christian pottage.