There were OT believers that did not have to through the priesthood, did not have to go through Israel, etc. to be saved. Ruth is a good example of that. Naomi lived a Godly life. It was not the Jewish religion that she saw, but the Godly life she saw. Thus Orpah went back to her idolatry, but Ruth's life had been changed. She gives one of the most beautiful salvation testimony's in the Bible:All were savd by same way, by the death of Jesus upon the Cross as atonement for their sins, but the OT believers were under an inferior relationship, as it was based upon physical blessings from the Lord concerning the promised land, while we in chuch age have allspiritual blessings in christ!
We are under a surer/better covenant, as we can go directly to God, something not able to be done in OT, as they needed to go through priesthood, but ALL of us now priests before God!
Ruth 1:16-17 And Ruth said, Intreat me not to leave thee, or to return from following after thee: for whither thou goest, I will go; and where thou lodgest, I will lodge: thy people shall be my people, and thy God my God: Where thou diest, will I die, and there will I be buried: the LORD do so to me, and more also, if ought but death part thee and me.