Exhort one another daily, while it is called Today; lest any of you be hardened through the deceitfulness of sin–Heb. 3:13
We cannot help but notice from this exhortation the deceitfulness of sin, the swiftness with which it can deceive us, and the urgency with which we must battle against it.
Sin lies to us, causing us to harden our hearts and draw away from God in unbelief (12). When we give in to any sin, we are not able to think as clearly and joyfully and trustingly as before.
Whether the sin is lust or anger or pride or greed, sin deceives us into thinking that satisfaction is found somewhere else than in God. It promises fulfillment through sensual pleasure, or putting others down, or lifting ourselves up, or gaining more “stuff.”
But this is a lie. True and lasting joy is only found in the path and presence of the living God. Everything else is just a dead, limp substitute that has been painted and polished and perfumed to look enticing.
But how swiftly we give in to the lie! The writer reminds us that we need daily exhorting, lest sin have its hardening effect on our hearts. We can walk faithfully for a week, a decade, or half a lifetime and then suddenly fall in a day! Constant vigilance, and the exhortation of others, is needed in order to avoid sin’s pitfalls today, no matter how successful we’ve been so far.
Finally, the writer presses the urgency of our situation. It is only called “Today” for 24 hours! Then tomorrow will come, and soon the end of all days. Do not put off the vital work of repentance and faithfulness. Today is already almost over, and our Lord that much closer to returning.(From “A Good Thing”)