LOL, My opening line for this post was "We need to trust God, not man..." Your reply is, trust man...

The sabbath is one of the Ten Commandments. Also, read Hebrews if you want to understand the new priesthood, "But Christ being come an high priest of good things to come, by a greater and more perfect tabernacle, not made with hands, that is to say, not of this building; Neither by the blood of goats and calves, but by his own blood he entered in once into the holy place, having obtained eternal redemption for us." Hebrews 9:11-12

As for becoming Jews, no, of course not. I am neither from the tribe of Judah nor do I think Judaism is a good idea. However, this does not negate the fact that believers who were formerly gentiles get grafted into God's people, Israel.

"Wherefore remember, that ye being in time past Gentiles in the flesh, who are called Uncircumcision by that which is called the Circumcision in the flesh made by hands; That at that time ye were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of promise, having no hope, and without God in the world:
But now in Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ." Ephesians 2:11-13

Please read the actual words above. We used to be gentiles.
Now, we are

• No longer Gentiles
• No longer without Christ
• No longer aliens from the commonwealth of Israel
• No longer strangers from the covenants of promise
• No longer having no hope
• No longer without God

If we are no longer aliens from the commonwealth of Israel, what then are we? Joined to Israel, aka grafted in. Why is this important? We need to be in covenant with God, i.e. not strangers from the covenant of promise. The new covenant is between God and Israel...

"Behold, the days come, saith the Lord, that I will make a new covenant with the house of Israel, and with the house of Judah: Not according to the covenant that I made with their fathers in the day that I took them by the hand to bring them out of the land of Egypt; which my covenant they brake, although I was an husband unto them, saith the Lord: But this shall be the covenant that I will make with the house of Israel; After those days, saith the Lord, I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people." Jeremiah 31:31-33

That is the New Covenant that God speaks of, not the made up one the modern church pretends exists. Please, read your bible, not the books of men. Allow the Spirit of truth to guide you into truth ("Howbeit when he, the Spirit of truth, is come, he will guide you into all truth: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will shew you things to come." John 13:16) (since that is the reason it is given) rather than exalted men to lead you astray.