"They show that the requirements of the law are written on their hearts, their consciences also bearing witness, and their thoughts now accusing or excusing them." Romans 2:15
The principal means which God uses in conversion is that of our conscience; and indeed without this, all the rest are in vain. Outward afflictions are of service only as they tend to awaken the conscience from its lethargy to a faithful discharge of its duty. It is conscience which makes the sinner sensible of his misery and scourges him. The lashes of a guilty conscience are intolerable and some under them have chosen suicide rather than life.
Conscience is a serpent in the sinner's breast, which bites and gnaws his heart and he can no more avoid it than he can fly from himself!
If a person has never been tortured with its remorse, they not congratulate themselves or think it good, for they are not innocent! Their conscience will not always sleep! It will not always lie torpid and inactive, like a snake benumbed with cold in their breast!
It will awaken them either to their conversion or condemnation!
Either the fire of God's wrath flaming from His law will enliven the conscience in this world to sting the unconverted person with medicinal anguish; or the unquenchable fire of His vengeance in the lake of fire and brimstone will thaw it into life and then it will horribly rage in their breast, and diffuse its tormenting poison through their whole frame! And then it will become a never-dying worm, and prey upon their hearts forever!
- Samuel Davies