In Matthew 10 we find Jesus instructing His representatives, those He is sending out - His disciples.
It is not unreasonable that we should fear God. This is Jesus Christ uttering this and He says that we are to fear Him who is able to destroy both body and soul in hell. The reason is because He is the only one who can revoke the judgment of gehenna fire. The wages of sin are death - in gehenna fire. And, if we are going to escape this punishment, then we can see that it is very closely tied-in to whether or not we actually fear God.
Why is that so? What does the fear of God have to do with escaping a judgment that would otherwise take us into the Lake of Fire?
There is some encouragement here in the series of verses in Matthew 10. It indicates that, if one really fears God, then there is no need to be fearful of others. Proverbs 29:25 very plainly tells us that, The fear of man is a snare. This is something by which we do not want to be entrapped.
I think it obvious, in the context of Matthew 10 and beginning with verse 27, that He is talking about fear in the sense of dread.The reason that we are not to fear men is because the worst that they can do cannot even begin to match the worst that God can do! The basis for this is what God is: omnipotent, omniscient, and in Him are the issues of life and death!
Brethren, this is our calling. We have been chosen by Him. This is our only chance. We are an insignificant number and we are even more insignificant personally. And yet we have been given this calling by Him. The world population is somewhere in the vicinity of 5,200,000,000 people. And out of this total are a minuscule number of those who are truly converted and have been given the Spirit of God. This is not something that we want to pass up! The fear of God is crucial to our salvation!