To fall into the hands of the living God is here a metaphor for facing God’s condemnation. We might use an expression like this describe the dreadful condition of someone who is completely overpowered by an enemy set on doing them harm.
Let men and women humble themselves and consider what an offence it is to the Lord to go on rejecting his mercy. Let us fear to provoke him to wrath for he cannot engage him in battle for a moment with any prospect of success. Let us not risk a further day in unbelief with our souls in eternal jeopardy. We are poised over hell and it is only the hand of God that prevents us from falling.