Many Christians find it a fearful thing to share Christ with the lost, so how can Christians overcome their fear in sharing the gospel?
Fear of Man
Many Christians find it a fearful thing to share Christ with the lost, so how can Christians overcome their fear in sharing the gospel? To begin with, we’re not the only ones to have a fear of man over the fear of God. Moses, Isaiah, and many others held that fear too. Even the Father of the Faithful, Abraham compromised the truth in saying his wife Sarah was his sister when he entered Egypt. Abraham feared they would kill him and take his wife for themselves since Sarah was still so beautiful. He covered his own tracks but put Sarah at risk. Either way, it was a half-truth, but a half-truth is really a whole lie, but who among us hasn’t let the fear of man overcome the fear of God? Therefore, we cannot be too hard on Abraham. Abraham said, “I did it because I thought, ‘There is no fear of God at all in this place, and they will kill me because of my wife’” (Gen 20:11), and you know what? Abraham was right. There was no fear of God in Egypt, but his fear of man was stronger than his faith in God’s protective hand.
Fear of God
To have godly wisdom, all we have to do is pray and He will give it to us (James 1:5), but we can never hope to have any true, godly wisdom until we first learn to fear God. To fear God does not mean you fear His striking you dead at any moment. To fear God is to hold Him in the highest regard and revere His Name, His Word (the Bible) and all of His precepts and commandments. Obeying God is the wisest thing we could ever do, because “The fear of the LORD is the beginning of wisdom; all those who practice it have a good understanding. His praise endures forever” (Psalm 111:1)! You can’t even begin getting wisdom at all until you first fear (revere) the Lord God and that means coming to trust in the Lord Jesus Christ as your Savior. Solomon, the wisest man on earth (next to Jesus of course) wisely stated that “The fear of the LORD is the beginning of wisdom, and the knowledge of the Holy One is insight” (Prov 9:10).
The solution to having a lack of wisdom is simply to ask God. James wrote, “If any of you lacks wisdom, let him ask God, who gives generously to all without reproach, and it will be given him” (James 1:5). Wisdom cannot even start without having the fear of God. Wisdom begins with fearing God. Jesus’ wisdom tells us that we should “not fear those who kill the body but cannot kill the soul. Rather fear him who can destroy both soul and body in hell” (Matt 10:28). He is the One to fear, for man has no power beyond the grave. God does. If you fear God, you’ll have no fear of man, but the fear of man can so easily override the fear of God. The fear of man is when we are more worried about how we will look before others that we will look before God, and that’s something should not happen. Should we really be that concerned about what others will think about us more than what God knows about us? As for me, I plead guilty. I’ve done this. Been there…done that…bought the T-shirt. But we can overcome that.
Rescue the Perishing
If you saw a house on fire in the early morning and knew the occupants were asleep, you’d do anything to try and warn them. You would surely ring the doorbell, pound on the door, scream at the top of your lungs, and even break a window to get in and warn them. At that point, you’re not worried about what the neighbors will think. You fear the fire will consume them and you will (I hope) do just about anything to save their lives, but friends, there is a greater fire coming than this house fire, because it will eventually go out. There is coming a fire that cannot be quenched (Mark 9:48). Since God has sparred us from His righteous wrath (Rom 5:9; 1 Thess 5:9), how can we not warn others and pray that God spars their lives? We must warn them “They will suffer the punishment of eternal destruction, away from the presence of the Lord and from the glory of his might” (2 Thess 1:9). Since God did not even spare His own Son from His wrath (Rom 8:32), what makes “good people” think they can slide into heaven without Jesus? We must be bold and courageous and willing to be despised by others for His name’s sake, but some will be saved by sharing the gospel. Not many, but at least some (Matt 7:21-23). Just ponder or think of their eternal destiny without Christ? Remember that they too are created in the image of God (Gen 1:27; 5:1, 9:6; Matt 19:14; Eph 4:24). 
Evidence of Wisdom
We can see real, tangible evidence of a person who has godly faith. James asks, “Who is wise and understanding among you? By his good conduct let him show his works in the meekness of wisdom” (James 3:13). Our conduct before others and in private, done in meekness, is evidence of godly wisdom, but we are not the source! God tells us that “the wisdom from above is first pure, then peaceable, gentle, open to reason, full of mercy and good fruits, impartial and sincere” (James 3:17). Wisdom is not brow-beating someone to prove a point or winning a debate, but winning people to Christ by our love for one another (John 13:34-35). When lost sinners see such humility and transparency in us, they might be drawn to hear more about Jesus, but we must beware of the wisdom of humanity since it’s not like “the wisdom that comes down from above, but is earthly, unspiritual, demonic” (James 3:15). In the end, no human imagination, philosophy, or wisdom has ever solved one problem for humanity. In fact, earthly wisdom has led us to a world bent on destruction.
Part of the wisdom God imparts to us is the imperative command to make disciples (Matt 28:18-20), and to have God’s desire be our desires in that He desires none should perish. If you have never trusted in Jesus Christ, then you will face the wrath of God on judgment day (Rev 20:12-15), and that’s the thing you should fear the most. It should be out of love that we warn people about their eternal destination without Christ. When God judges a person who has rejected Christ, there is no chance for repentance then. Their greatest fear will come true. They will face torment and eternal separation from God. Never again will they see their saved loved ones. There is no reason to delay in their trusting in Christ right now. Tell them before it’s too late. By God’s grace, they might believe on the Lord Jesus Christ, confess Him with their mouth (Rom 10:9-13), and then find a Bible-believing church and get baptized (Heb 10:24-25). Take the advice of the author of Hebrews who pleads with the lost sinner: “Today, if you hear his voice, do not harden your hearts as in the rebellion” (Heb 13:5). Make that decision today, right now, while it is still called today” (2 Cor 6:2).
Here is some related reading for you: I’m Shy, So How Can I Witness for Christ? 
Resource – Scripture quotations are from The Holy Bible, English Standard Version® (ESV®), Crossway Bibles. (2007). ESV: Study Bible: English standard version. Wheaton, Ill: Crossway Bibles. Used by permission. All rights reserved.