Not a single person can come to God for salvation unless God draws him through Jesus Christ. Saving faith is a very special faith, existing in an individual only because of a miraculous gift from God. It is not generated internally by logical human reason, common sense, or human experience. If faith were not a graciously and freely given gift of God, but rather our own internally generated response to hearing the gospel, God would be indebted to us. In other words, He would owe us because we, on our own, provided the faith to begin and continue in His way.
Notice the conversation Jesus had just moments before what is recorded in John 6:44:
"Do not labor for the food which perishes, but for the food which endures to everlasting life, which the Son of Man will give you. . . ." Then they said to Him, "What shall we do, that we may work the works of God?" Jesus answered and said to them, "This is the work of God, that you believe in Him whom He has sent." Therefore they said to Him, "What sign will You perform then, that we may see it and believe You? What work will You do?" (John 6:27-30)
Jesus clearly says that believing in the One God sent—Jesus Christ—is God's work! He clarifies this in verse 44, declaring that God is that specific belief's Originator and Source; otherwise, we would not have the faith of which He speaks. As usual, the Jews did not completely understand.