Non-Jews could share in God's promise to Abraham and his descendants by

According to the Jewish faith, non-Jews can share in God's promise to Abraham and his descendants by upholding the faith of Abraham. This means that non-Jews can become righteous and follow the teachings and beliefs of Abraham, which include the belief in one God and the importance of leading a virtuous life. It does not necessarily require non-Jews to obey all the laws like Abraham or to convert to Judaism. Rather, non-Jews can achieve righteousness and be considered righteous in the eyes of God by following the moral principles and values that Abraham embodies.