The following is an excerpt from The MacArthur New Testament Commentary on John 6.

No one can come to Me unless the Father who sent Me draws him; and I will raise him up on the last day. (John 6:44)

Jesus uttered some very solemn words: “No one can come to Me unless the Father who sent Me draws him,” emphasizing man’s helplessness and utter inability to respond to Him apart from God’s sovereign call. Unbelievers are unable to come to Jesus on their own initiative. If God did not irresistibly draw sinners to Christ, no one would ever come to Him.

To explain how lost sinners supposedly have the power to accept or reject the gospel of their own free will, some theologians introduce the concept of prevenient grace. Millard J. Erickson explains,

As generally understood, prevenient grace is grace that is given by God to all men indiscriminately. It is seen in God’s sending the sunshine and the rain upon all. It is also the basis of all the goodness found in men everywhere. Beyond that, it is universally given to counteract the effect of sin.… Since God has given this grace to all, everyone is capable of accepting the offer of salvation; consequently, there is no need for any special application of God’s grace to particular individuals. (Christian Theology, 3:920)

But the Bible indicates that fallen man is unable, of his own volition, to come to Jesus Christ. Unregenerate people are dead in sin (Eph. 2:1; Col. 2:13), slaves to unrighteousness (John 8:34; Rom. 6:6, 17, 20), alienated from God (Col. 1:21), and hostile to Him (Rom. 5:10; 8:7). They are spiritually blind (2 Cor. 4:4) captives (2 Tim. 2:26) trapped in Satan’s kingdom (Col. 1:13), powerless to change their sinful natures (Jer. 13:23; Rom. 5:6), unable to please God (Rom. 8:8), and incapable of understanding spiritual truth (1 Cor. 2:14; cf. John 14:17). Although the human will is involved in coming to Christ (since no one is saved apart from believing the gospel—Mark 1:15; Acts 15:7; Rom. 1:16; 10:9–15; Eph. 1:13), sinners cannot come to Him of their own free will. (Moreover, a comparison of verse 44 with verse 37 shows that God’s drawing cannot apply to all unregenerate people, as proponents of prevenient grace argue, because verse 37 limits it to the redeemed whom God has given to Christ.) God irresistibly, efficaciously draws to Christ only those whom He chose for salvation in eternity past (Eph. 1:4–5, 11).

Once again, Jesus repeated the wonderful promise that all whom the Father chooses will be drawn, will come, will be received, and He will raise them on the last day (vv. 39–40, 54). Everyone who comes to Christ will be kept by Him; there is no possibility that even one elect person given to Him by the Father will be lost (see the discussion of v. 39 above).