John 6:41-46 — The Jews then murmured at Him, because He said, I am the bread which came down from heaven.
And they said, Is not this Jesus, the son of Joseph, whose father and mother we know? how is it then that He saith, I came down from heaven?
Jesus therefore answered and said unto them, Murmur not among yourselves.
No man can come to Me, except the Father which hath sent Me draw him: and I will raise him up at the last day.
It is written in the prophets, And they shall be all taught of God. Every man therefore that hath heard, and hath learned of the Father, cometh unto Me.
Not that any man hath seen the Father, save He which is of God, He hath seen the Father.
At some point, maybe here, some of the crowd followed Jesus into the synagogue. Or, tarting in verse 41, Jesus may have been speaking to a different audience who had not heard, but had heard of, what He said to the crowd in verses 26-40.
In John, the "Jews" are always antagonistic to Jesus. In this Gospel, the Jews were the inhabitants of Jerusalem and Judea.
They knew His words, "I am the bread which came down from heaven" meant He had a Divine origin (John 3:31).
The Jews did not know of the virgin birth at this time, although it had been prophecied (Isaiah 7:14).
In verse 37-40, the Father gives the Son those who come to Him. In verse 44, the Father draws them.
Draw = exerting power to impel an object. The same word is used in John 18:10; 21:6; 21:11. In this case, it's the Holy Spirit's convicting.
But we preach Christ crucified, unto the Jews a stumblingblock, and unto the Greeks foolishness; but unto them which are called, both Jews and Greeks, Christ the power of God, and the wisdom of God (1 Corinthians 1:23-24).
But if someone doesn't believe, it is his own fault. For what shall it profit a man, if he shall gain the whole world, and lose his own soul? (Mark 8:36)
The quote in verse 45 is from Isaiah 54:13 — And all thy children shall be taught of the LORD; and great shall be the peace of thy children.
Jeremiah 31:33-34 — 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. And they shall teach no more every man his neighbour, and every man his brother, saying, Know the LORD: for they shall all know Me, from the least of them unto the greatest of them, saith the LORD: for I will forgive their iniquity, and I will remember their sin no more.
It is a very notable principle in connection with the ways of our Lord Jesus Christ with men that if a soul came to Him who was honestly, earnestly, seeking to know the truth, He undertook to make that truth just as simple as possible so that the wayfaring man could understand. On the other hand, if the Savior presented something which was difficult for the natural mind to receive, and men, instead of recognizing their need and coming to Him for explanation, assumed a haughty, unbelieving attitude, He invariably seemed to make the truth more difficult instead of making it simpler. That is to say, if men will not have the truth of God when it is presented to them but deliberately choose to follow the path of error, they will be blinded to the very truth itself — Addresses on the Gospel of John, by H.A. Ironside, page 255
Jesus says that no one could know His true identity unless the Father revealed it to him.
To come to Jesus, one must be drawn by, taught by, heard from and learned from the Father. But even so, nobody has direct access to the Father.