The prophet Isaiah ultimately wrote of the children of Israel:
All we like sheep have gone astray; we have turned—every one—to his own way… (Isaiah 53:6).
By the end of the Era of Moses, the children of Israel were a divided kingdom. They had even divided the religion given to them by God on Mount Sinai. Some worshipped in places other than Jerusalem, once again bringing in the worshipped idols.
By the time of Jesus, Israel (known by then as the Jews) was worshipping in different denominations of their religion, Judaism. The Sadducees, the Pharisees and the Essenes were different denominations of Judaism with various and conflicting beliefs and practices. The children of Israel had been mixing man-made teachings with the teachings of God.
Jesus, as He began His earthly ministry around 29 A.D., said to the Jews,
So for the sake of your tradition you have made void the Word of God. You hypocrites! Well did Isaiah prophesy of you, when he said: “‘This people honors me with their lips, but their heart is far from me; in vain do they worship me, teaching as doctrines the commandments of men’” (Matthew 15:6–9).
Jesus would spend the rest of His time on earth teaching people who God is and how we are to live.
Have I been with you so long, and you still do not know me, Philip? Whoever has seen me has seen the Father. How can you say, ‘Show us the Father’? Do you not believe that I am in the Father and the Father is in me? The words that I say to you I do not speak on my own authority, but the Father who dwells in me does his works. Believe me that I am in the Father and the Father is in me, or else believe on account of the works themselves. Truly, truly, I say to you, whoever believes in me will also do the works that I do… (John 14:9–12).