Arthur W. Pink in one of his writings states:
It is true that believers are bidden to fear Him which is able to destroy both body and soul in Hell (Matt. 10: 28), yet it should be pointed out that there is a vast difference between fearing God and dreading eternal punishment: in the parallel and fuller passage Christ added, yea, I say unto you, fear Him (Luke 12:5)-not fear Hell. one of the covenant promises which God has made concerning His elect is, I will put My fear in their hearts, that they shall not depart from Me (Jer. 32:40), and that is a filial fear, a respect for His authority, an awesome veneration of His majesty; whereas the fear of the unregenerate is a is a servile, anxious and tormenting one. The holy fear of the righteous causes them to be vigilant and watchful against those ways which lead to destruction, but the fear of the wicked is occupied only with destruction itself: the one is concerned about evils which occasion God’s wrath; the other is confined to the effects of His wrath. But the exercise of faith and the operations of filial fear are not only principles which regulate the saint: the love of Christ constrains him; gratitude unto God for His wondrous grace has a powerful effect upon his conduct.
(Eternal Security: It’s Opposition by Arthur W. Pink)