Hebrews 3:12–13 (ESV) — 12 Take care, brothers, lest there be in any of you an evil, unbelieving heart, leading you to fall away from the living God. 13 But exhort one another every day, as long as it is called “today,” that none of you may be hardened by the deceitfulness of sin.
It is the Author’s observation, that sin is so deceitful, and hardens the heart against the sweet motions of the Spirit so quickly, that we need daily exhortations to guard against it.
One does not need to put butter in a blast chiller to get it to harden, they need only remove it from any heat source – just leave it alone.
This is how the souls of men are. There is an inertia to our remaining sinfulness. Even nature teaches us that a “body at rest tends to stay at rest”. If it is not moved – it will not move. Simply left to themselves, not brought near to the flame, our hearts congeal and harden without any further influence. Time in the Word, time in prayer, exposing ourselves to spiritual matters from reliable sources which bring us before the throne of grace again to warm our hearts is a constant need, not some mere, perfunctory religious duty.
Beloved, find some time today, some place, to bring your heart near the flame of Christ’s loving grace and mercy so as to melt you afresh. It takes only the shortest amount of time for the hardness to begin settling in – for sin to deceive us that something else is more important, more necessary.