God’s judgment will be a fearful thing for all men. In fact, according to Revelation 6:16, men will want the mountains and rocks to fall on them rather than to suffer the wrath of God. Fear will also grip the believer, but their reaction will be much different than evil men.
When I heard, my belly trembled; my lips quivered at the voice: rottenness entered into my bones, and I trembled in myself, that I might rest in the day of trouble: when he cometh up unto the people, he will invade them with his troops.
Although the fig tree shall not blossom, neither shall fruit be in the vines; the labour of the olive shall fail, and the fields shall yield no meat; the flock shall be cut off from the fold, and there shall be no herd in the stalls:
Yet I will rejoice in the LORD, I will joy in the God of my salvation. — Habakkuk 3:16-18 (KJV)
Those who are saved by faith will rejoice, even in times of fear, when judgement comes. They know their salvation is of God and he will be certain to rescue them.
It is a fearful thing to fall into the hands of the living God. — Hebrews 10:31 (KJV)
Yes, it is a fearful thing, unless you are one of His.