Hebrews 10:30,31

Heb. 10:30-31. For we know him that hath said, Vengeance (belongeth) unto me, I will recompense, saith the Lord. And again. The Lord shall judge his people. (It is) a fearful thing to fall into the hands of the living God.

In the awesome published sermon, "Men Naturally God's Enemies" Edwards proves it is "a fearful thing" indeed by this text.

Hast not he that made you, and gave you your strength, and your courage, get your strength and courage in his hands? Is it a hard thing for him to overcome it? Consider God has made your soul; and he that made it knows how to punish it to what degree he will. He will fill it with misery; he can bring what degree of sorrow, and anguish, and horror he will. And he that made your body can bring what torments he will upon it. He has made every vein and sinew; and has every one in his hands, and he can fill every one as full of torments as he will. God, who made you, has given you a capacity to bear torment; and he has that capacity in his hands; and he can enlarge it, and make you capable of more misery, as much more as he will. If God hates any one, and sets himself against him as his enemy, what cannot he do with him? How dreadful must it be to fall into the hands of such an enemy! Surely, "It is a fearful thing to fall into the hands of the living God," Hebrews 10:31.

Heb. 10:32