Sinners will often seem like formidable giants when we are planning to witness to them. The key is to realize that you are made strong in your weakness. Your fear will cause you to pray, and will then become your strength. So use fear to drive you to your knees. Another key is to remember the fate of the sinner if he dies in his sins. If God gives him justice he will end up in hell. Take courage, let love swallow your fears, and make your approach. Be like David—he ran toward Goliath (see 1 Sam. 17:48). You will learn that, with few exceptions, your fears will not be realized.
Matthew Henry said, “Difficulties that are in the way of salvation dwindle and vanish before a lively, active faith in the power and promise of God. All things are possible, if they are promised, to him that believes; but carnal sense and carnal professors are not to be trusted. Unbelief overlooks the promises and power of God, magnifies every danger and difficulty, and fills the heart with discouragement. May the Lord help us to believe! We shall then find all things possible.”
Numbers 13:31 But the men who had gone up with him said, “We are not able to go up against the people, for they are stronger than we.”32 And they gave the children of Israel a bad report of the land which they had spied out, saying, “The land through which we have gone as spies is a land that devours its inhabitants, and tall the people whom we saw in it are men of great stature. 33 There we saw the giants ( the descendants of Anak came from the giants); and we were like grasshoppers in our own sight, and so we were in their sight.”