There are rungs of ascending spiritual levels that one can achieve as a Noahide (Observant Gentile).
The most basic level of righteousness, which G-d expects from every Gentile, is to refrain from any actions that would transgress any of the Seven Noahide Commandments, regardless of what your beliefs are about the source or basis of those commandments.
Thus, adding on observance of the eternal 7 Noahide Commandments to whatever you are presently following is a very positive and worthwhile step, that will certainly bring you into a more personal relationship with G-d.
Beyond the obligation to observe just the letter of the Seven Commandments, a Gentile can progress further to take on the Torah-based faith of the Noahide Code.
The Noahide Code as a faith extends beyond the general concept that there are Seven Noahide Commandments, and it includes a set of basic principles about G-d, prophecy, and the Torah of Moses.
By accepting and following the Torah-law details for the Seven Noahide Commandments because they were given directly by G-d in the Written Torah and the Oral Torah, a Gentile can merit the reward of eternal life of the future World to Come.
Certainly, a Noahide on this higher level is anxiously waiting for the Messiah son of David (the “Moshiach,” in Hebrew) who is promised by G-d in the Hebrew Scriptures. Also, he/she recognizes that every Gentile has a personal responsibility to repent directly to G-d for any transgressions of the Seven Commandments that are done, G-d forbid. A person’s sincere repentance brings G-d’s forgiveness, and His cleansing of the person’s soul from the stain of a sin.
One of the commandments that G-d gave through Moses is that all Gentiles should observe the Seven Commandments of Noah. In fact, the only written proof we have that there are Noahide Commandments and a Noahide Covenant is that G-d instructed Moses at Mount Sinai to write about the generations from Adam to Noah in the Torah’s Book of Genesis, and to preserve the details of those commandments within the Oral Torah.
So ultimately, that is their basis from that time on. The pious individuals of the nations (who earn a place in the World to Come) are those who follow the Seven Commandments because G-d commanded them to Noah, and because all Gentiles must follow those precepts according to the details of the Noahide Code that G-d commanded through Moses.
Therefore, a faithful Noahide accepts that G-d revealed Himself at Mount Sinai to the entire Jewish nation (at least 3 million people), and that Moses was a true prophet and the receiver and transmitter of the Torah.
Unlike Torah-true Noahidism and Judaism that were given by G-d, there are man-made religions in the modern world that have a great many recognized branches and sub-branches. In addition, one must admit that each individual has his/her own personal interpretations of his own religion, which influence exactly what he/she believes and practices.
The compatibility of this with the strict letter of the Noahide Commandment that forbids idolatry must be considered objectively on a case-by-case basis.
To go into more depth on this issue, you should read the book, “The Divine Code,” Volume I, by Rabbi Moshe Weiner.
By way of introduction, consider the first of the Principles of Torah Faith enumerated by Maimonides, which includes the following:
“… there is in existence a Being Perfect in respect of all modes of existence, Who is the Cause of all things in existence, through Whom their existence is possible, and from Whom their existence ensues.”
This can be expressed as the principle of the Truth of G-d’s Being, which supersedes and transcends any other possible Truth, and by virtue of His True Being all the spiritual and physical creations are brought into existence.
The Noahide principles (some of which are incorporated in the first Noahide Commandment, which prohibits idolatry) recognize the truth of the absolute unity and non-physicality of G-d.
Historically, the Noahide Code continued to have a following throughout history up until the destruction of the Second Temple in Jerusalem and the exile of the Jewish People, who up until then had provided a main source of religious instruction and inspiration for the Noahides.
Now that the time for the end of the exile of the Divine Presence from Jerusalem has arrived, large numbers of Gentiles are again becoming motivated to return to the Noahide faith.
By Rabbi Michael Schulman