Hebrews 3:12

Βλέπετε ἀδελφοὶ μή ποτε.… “Take heed lest haply” as in Hebrews 12:25; Colossians 2:8, for the more classical ὁρᾶτε μὴ. It is here followed by a future indicative as sometimes in classics. ἔν τινι ὑμῶν, the individualising, as in Hebrews 3:13 indicates the writer's earnestness, whether, as Bleek supposes, it means that the whole Christian community of the place is to be watchful for the individual, may be doubted; although this idea is confirmed by the παρακαλεῖτε ἑαυτοὺς of Hebrews 3:13. What they are to be on their guard against is the emergence of καρδία πονηρὰ ἀπιστίας ἐν … ζῶντος, a wicked heart of unbelief manifesting itself in departing from Him who is a living God. ἀπιστίας is the genitive of quality = a bad, unbelieving heart; whether the wickedness proceeds from the unbelief, or the unbelief from the wickedness, is not determined. Although, from the next verse it might be gathered that unbelief is considered the result of allowed sin: i.e., it is when the heart is hardened through sin, it becomes unbelieving, so that the psychological order might be stated thus: sin, a deceived mind, a hardened heart, unbelief, apostasy. The main idea in the writer's mind is that unbelief in God's renewed offer of salvation is accompanied by and means apostasy from the living God. In the O.T. Jehovah is called “the living God” in contrast to lifeless impotent idols, and the designation is suggestive of His power to observe, visit, judge and succour His people. In this Epistle it occurs, Hebrews 9:14; Hebrews 10:31; Hebrews 12:22. To object that the apostasy of Jews from Christianity could not be called “apostacy from God” is to mistake. The very point the writer wishes to make is just this: Remember that to apostatize from Christ in whom you have found God, is to apostatize from God. It is one of the ominous facts of Christian experience that any falling away from high attainment sinks us much deeper than our original starting point.