A.T. Robertson Commentary Hebrews 10:31

"It is a fearful thing to fall into the hands of the living God." — Hebrews 10:31 (ASV)

A fearful thing (φοβερον). Old adjective (from φοβεω, to frighten). In N.T. only in Heb. (10:27,31; 12:21). The sense is not to be explained away. The wrath of God faces wrongdoers.

To fall (το εμπεσειν). "The falling" (articular infinitive second aorist active of εμπιπτω, to fall in, followed here by εις). We are not dealing with a dead or an absentee God, but one who is alive and alert (3:12).