“There is nothing here to suggest the Greeks could join without circumcision, or dietary restrictions. Nothing short of becoming fully Jewish. Either you were a Jew or a Gentile.”
Matt. 8:8-13, “The centurion answered and said, Lord, I am not worthy that thou shouldest come under my roof: but speak the word only, and my servant shall be healed. For I am a man under authority, having soldiers under me: and I say to this man, Go, and he goeth; and to another, Come, and he cometh; and to my servant, Do this, and he doeth it.
When Jesus heard it, he marvelled, and said to them that followed, Verily I say unto you, I have not found so great faith, no, not in Israel. And I say unto you, That many shall come from the east and west, and shall sit down with Abraham, and Isaac, and Jacob, in the kingdom of heaven, but the children of the kingdom shall be cast out into outer darkness: there shall be weeping and gnashing of teeth. And Jesus said unto the centurion, Go thy way; and as thou hast believed, so be it done unto thee. And his servant was healed in the selfsame hour.”
Nothing about circumcision or dietry laws here. Just a clear statement of faith and the statement of Jesus that Gentiles will be included in the kingdom based on faith, like the Roman Centurian.
Indeed, the Centurion...
Judaism was always open to converts. There is a difference between becoming a convert and becoming a second-class "graft."