There is no need for any Christian to worry about whether his witness will be effective. Pray these three things and trust the Lord to do His work.
For the Holy Spirit to continue His work long after your witness. If the Holy Spirit has led you with boldness to witness to someone, you can believe that He has also been ministering to that person—that is, all along the way He has been preparing that person’s heart to hear the gospel. Bit by bit He has been liberating that one’s mind and heart from the power of Satan; He has been helping them to see their own lostness, to see that time is short, and to see God’s love.
Let me urge you to keep praying for that lost one. Pray that throughout your witness and even after you witness, that the Holy Spirit would continue His ministry of drawing that one to Christ. Our witness may be short, or in some cases long and continuous; but prayer must continue even longer; and the ministry of the Holy Spirit will continue longer still. So pray that way. Pray that the Holy Spirit would carry on His work long after our witness and prayers have ended.
For the Holy Spirit to grant repentance to the ones you witness to. This request I think should be the one we focus on most, for without repentance people remain in their sin. But with repentance we leave the old life behind and we begin to trust in the Savior. Repentance therefore is the key that unlocks the door to receive God’s grace. Moreover, it is the way out of darkness and into the light. According to 2 Timothy 2:26, repentance is what brings them to their senses so that they are able to escape the snare of the devil.
Let us pray then in this regard (as 2 Tim. 2:25 indicates), that God will grant them repentance so that they may know the truth. And let us take note of what Jerry Wiles has said: “You can lead people to the light. But only the Holy Spirit can compel them to open their eyes. You can speak words of truth to others. But only the Holy Spirit can open their ears and their hearts to truly hear your message.”11 He does it through repentance, which He grants them. Thus repentance is a gift of God. It comes to us according to the exceeding riches of His grace in His kindness toward us in Christ Jesus (Eph. 2:7-9). Praise God for His wonderful gift of repentance and grace, given to all those who will receive it.
For the Holy Spirit to help those you witness to, to make a decision for Christ. I have often found in my witnessing experience that though the Holy Spirit has helped people to see the truth, they are not always willing to repent fully, because they still have doubts and fears about making a decision for Christ. They will often express that the gospel “makes sense” and that they “want to” receive Christ but that they are just “not ready” or they just “don’t know for sure yet.”
Jerry Wiles, in his book, suggests that if this happens—and it almost always does—we should ask the person if we can pray with him that he would have the freedom to make the decision. Here is his suggested prayer:
Heavenly Father, I ask You to free [the persons name], in the name of Jesus, from any tormenting thoughts or plaguing doubts that are keeping [the persons name] from making a decision to receive Your Son, the Lord Jesus Christ, in his heart as his Savior and Lord12
11 Jerry Wiles, How to Win Others to Christ, p. 30.
12 Ibid., p. 136.