God made Himself known to Adam and Eve in the Garden which is His purpose for our creation: to know Him.
After sin enters the world God’s plan is to systematically reveal Himself to the descendants of Adam and Eve. Hence he calls Abraham to know Him. From Abraham God makes Himself known to Israel. With His work in Israel some believe in Him and some don’t. But He continues to work in the midst of Israel to make Himself known.
Then the Messiah comes and after His resurrection and subsequent ascension God does to the rest of the world what He did to Israel. He works in our midst to make Himself known. Some believe and some don’t but He works in each generation to make Himself known.
So you can see that God’s desire is to make Himself known and that He has given us a pattern of that revelation. Hence in the life of Israel He gives them His Law, Priests to administer the Law, Prophets to preach His Word and Kings to rule.
Now in His Son the Messiah are all of these contained: the Law, administrator of the Law, the teacher of His Law and King to rule over the people.
In each case some people believe and some don’t but God rules over all the people and works in our midst to bring forth salvation and therefore a reconciliation and knowledge of Himself.
Finally, as He rules over Israel, He was their God and they were His people, now He rules over the peoples of the world, He is our God and we are His people. Thus He works in the midst of this massive congregation to bring forth salvation as He did in Israel.