J.I. Packer, in his excellent treatise Evangelism and the Sovereignty of God, states:

“The sovereignty of God in grace gives us our only hope of success in evangelism.”

““Some fear that belief in the sovereign grace of God leads to the conclusion that evangelism is pointless, since God will save His elect anyway, whether they hear the gospel or not. This . . . is a false conclusion based on a false assumption. . . . So far from making evangelism pointless, the sovereignty of God in grace is the one thing that prevents evangelism from being pointless. For it creates the possibility–indeed, the certainty–that evangelism will be fruitful. Apart from it, there is not even a possibility of evangelism being fruitful. Were it not for the sovereign grace of God, evangelism would be the most futile and useless enterprise that the world has ever seen, and there would be no more complete waste of time under the sun than to preach the Christian gospel.”

The effects of such confidence in the sovereign grace of God should, according to Packer, produce three things:

1. It should make us bold.

“You are not on a fool’s errand. You are not wasting either your time or theirs. You have no reason to be ashamed of your message, or half-hearted and apologetic in delivering it. You have every reason to be bold, and free, and natural, and hopeful of success. For God can give His truth and effectiveness that you and I cannot give it. God can make His truth triumphant to the conversion of the most seemingly hardened unbeliever. You and I will never write off anyone as hopeless and beyond the reach of God if we believe in the sovereignty of His grace.”

2. It should make us patient.

“It should keep us from being daunted when we find that our evangelistic endeavors meet with no immediate response. God saves in His own time, and we ought not to suppose that He is in such a hurry as we are. . . . We are tempted to be in a great hurry with those whom we would win to Christ, and then, when we see no immediate response in them, to become impatient and downcast, and then to lose interest in them, and feel that it is useless to spend more time on them; and so we abandon our efforts forthwith, and let them drop out of our ken. But this is utterly wrong. It is a failure both of love for man and faith in God.”

3. It should make us prayerful.

“Prayer . . . is a confessing of impotence and need, and acknowledging of helplessness and dependence, and an invoking of the mighty power of God to do for us what we cannot do for ourselves. In evangelism, we are impotent; we depend wholly upon God to make our witness effective; only because He is able to give men new hearts can we hope that through our preaching of the gospel sinners will be born again. These facts ought to drive us to prayer. The knowledge, then, that God is sovereign in grace, and that we are impotent to win souls, should make us pray, and keep us praying. What should be the burden of our prayers? We should pray for those whom we seek to win, that the Holy Spirit will open their hearts; and we should pray for ourselves in our own witness, and for all who preach the gospel, that the power and authority of the Holy Spirit may rest upon them.”