Your conscience reacts to the convictions of your mind and therefore can be encouraged and sharpened in accordance with God’s Word. The wise Christian wants to master biblical truth so that the conscience is completely informed and judges right because it is responding to God’s Word. A regular diet of Scripture will strengthen a weak conscience or restrain an overactive one. Conversely, error, human wisdom, and wrong moral influences filling the mind will corrupt or cripple the conscience.
John MacArthur