Christian, remember how many backers thy evil nature has. As for thy gracious life, it finds few friends beneath the sky; but thine original sin hath allies in every quarter. It looks down to hell, and it finds them there, demons ready to let slip the dogs of hell upon thy soul. It looks out into the world, and sees “the lusts of the flesh, the lusts of the eye, and the pride of life.” It looks around, and it seeth all kinds of men, seeking, if it be possible, to lead the Christian from his steadfastness. It looks into the Church, and it finds all manner of false doctrine ready to inflame lust, and guide the soul from the sincerity of its faith. It looks to the body, and it finds head, and hand, and foot, and all other members ready to be subservient to sin. I could overcome my evil heart if it had not such a mighty host of allies, but it makes my position doubly dangerous, to have foes without the gates, in league and amity with a foe more vile within.
C.H. Spurgeon