Search me, O God, and know my heart!Try me and know my thoughts! And see if there be any grievous way in me, and lead me in the way everlasting! (Psalm 139:23-24 ESV)
What tangles us up in temptations and gets us into serious trouble has less to do with the world out there than the world inside of us. We fail and fall because of our own hearts, and since the problem is internal and universal we see the damage done in all people.
I say that you can hardly turn to a single character, among the holy men described in the Bible, who did not, to his own horror and dismay, fall at one time or another. Noah planted a vineyard, and was one day found drunken. David committed adultery with the wife of Uriah. Peter denied his Lord thrice. What does this prove? It proves beyond a question that the most excellent of the earth have found that the root of all their sinfulness is within them; they never boasted of the purity or goodness of their hearts, they have all placed upon record the truth that, although Satan does much and the world does much, still after all the great enemy is always within us!
- J.C. Ryle, A Bad Heart
From the heart "flow the springs of life," Solomon tells us. This is why he also says it is paramount that we "keep it." If we do not take care of our hearts disaster awaits. A life of external discipline may give the appearance of strength, but it will not bear the fruit of faith. The heart, when left unchecked, can become the very thing that sinks us.
The heart is ready to be destroyed by its own passion, just as a ship is ready to be overturned by its sail. The heart sometimes sinks in sorrow, swells with anger, and abounds excessively with carnal joy. Passion transports beyond the bounds of reason; it is a kind of temporary madness which possesses a person. Lay the bit of restraint upon your passions—or your heart will run wild in sin; take heed of inflaming your spirits. Cut off all occasions that may awaken this fury. Take away the fuel which feeds this fire! When this viper of passion begins to gather heat, pray it down. Luther said that prayer takes down the swelling of the soul—and abates the heat of inordinate affections. How dangerous these fiery passions are! In a passion, Moses spoke unadvisedly with his lips (Psalm 106:33). A man in a rage is like a ship in a tempest—which has neither pilot, sails, or oars to help—but is exposed to the waves and the rocks. How many have lost their souls in such a storm!
- Thomas Watson, The Spiritual Watch
How do we "restrain" our passions, take away the fuel which feed the fire, and "pray down" this unrighteous heat in our hearts? I'm eager to talk about all of this at this weekend's Porterbrook Kansas Gospel Immersion Seminar. For now let me just point you to my favorite work on the subject. John Flavel's Keeping the Heart. You can read it online for free, or purchase a hard copy from WTSBooks.