The Trojan horse!
(Thomas Watson, "The Lord's Prayer")
"Deliver us from evil." Matthew 6:13
In this petition we pray to be delivered from the evil of our heart, that it may not entice us to sin.
The heart is the poisoned fountain, from whence all actual sins flow. "For from within, out of the heart of man, come evil thoughts, sexual immorality, theft, murder, adultery, coveting, wickedness, deceit, sensuality, envy, slander, pride, and foolishness." Mark 7:21-22
The cause of all evil lies in a man's own bosom — all sin begins at the heart! Lust is first conceived in the heart — and then it is midwifed into the world. Whence comes rash anger? The heart sets the tongue on fire. The heart is the shop where all sin is contrived and hammered out.
The heart is the greatest seducer, "Each one is tempted when he is carried away and enticed by his own lust." James 1:14. The devil could not hurt us — if our own hearts did not give consent. All that he can do is to lay the bait — but it is our fault to swallow it! How needful, therefore, is this prayer, "Deliver us from the evil of our hearts!"
It was Augustine's prayer, "Lord, deliver me from that evil man — myself!"
Beware of the bosom traitor — the flesh. The heart of a man is the Trojan horse — out of which comes a whole army of lusts! O let us pray to be delivered from the lusts and deceits of our own heart! "Keep your heart with all diligence, for out of it spring the issues of life!" Proverbs 4:23