"Though we have received forgiveness and obtained a good conscience, haveing been fully absolved, yet life is such that one who is standing today falls tomorrow. Therefore, although at the present moment we stand upright and with a clear conscience before God, we must go on to pray that He will not allow us to fall, defeated by trials and temptations.
"Temptation (or allurement) is of three kinds: by the flesh, the world, and the devil. We live in the flesh and carry the old Adam hanging around our necks; he is at work every day inciting us to unchastity, laziness, gluttony, and drunkenness, to greed and deceitfulness, to acts of fraud and deception against our neighbor -- in short, to all kinds of evil lusts that cling to our nature and to which we are stimulated by other people's company and example and by what we otherwise hear and see. All this often bruises and scorches even an innocent heart.
"Next comes the world, which hurts us by word and deed, and drives us to anger and impatience. In short, one sees nothing in the world but hate and envy, enmity, violence and injustice, disloyalty, revenge, cursing, abuse, slander, arrogance and pride, combined with excessive finery, flattery, fame, and power. No one is satisfied to be low on the ladder but wants to be at the top and visible to everyone.
"Now comes the devil as well, harassing us and fuming at us from all sides, concentrating his attacks especially where conscience and spiritual matters are at stake. His chief aim is to make us discard both God's Word and His works, to tear us away from faith, hope, and love, to draw us into misbelief, false security, and stubborn impenitence, or else to drive us into despair, denial of God, blasphemy against Him, and countless other horrible sins. These are the devil's traps and nets, or more exactly, the most venomously poisoned 'fiery darts' which not flesh and blood but Satan shoots into our hearts.
"These grave perils and great temptations, which every Christian must endure, are grievous even if they come singly one by one. They constrain us, as long we remain in this wretched life, where we are pursued, hounded, and harried on all sides, to cry out and pray every hour that God would not allow us to become faint and weary, and to fall back into sin, shame, and unbelief. Otherwise it is impossible to overcome even the very slightest temptation.
"'Leading us not into temptation' consists of God giving us the power and strength to resist it even though the tribulation itself is not turned aside nor put to an end. For not one of us can successfully bypass temptations and enticements as long as we are living in the flesh and the devil is lurking about. Nothing else is to be expected than that we shall suffer trials and temptations, yes, even find ourselves bogged in them. However, what we pray for here is that we may not fall down into them and be drowned. . . .
"None of us dare carelessly go about in a false sense of security as if the devil were far away. Instead, wherever we are, we should expect his blows and be ready to ward them off. Even if at the moment I am chaste, patient, kindly, and stand firm in the faith, yet this very hour the devil is likely to drive such a shaft into my heart that I can scarcely hold my own. For he is an adversary who never lets up, never tires, and no sooner has one attack ended than new and different ones begin.
"Your only help or comfort at such times is to hurry for refuge into the Lord's Prayer and to appeal to God from the heart, 'Dear Father, You have commanded me to pray; do not let me fall into this temptation.' You will then see the temptation lessening, until it finally admits defeat. On the other hand, if you try to save yourself by your own devices of thought and feeling, you will only make a bad situation worse and give the devil a better opening. For he has the head of a serpent; if he finds a gap through which his head can slip, the whole length of his body wriggles in unchecked. Prayer, however, can oppose him and drive him back." (Luther's Large Catechism, CPH 1978)
Such prayer is really nothing else than the voice of faith, which lays hold of God in Christ. It is such a sure and certain weapon against the devil, because the very Lord Jesus who has taught us to pray, and in whom we pray, has crushed that serpent's head and defeated him forever. He also intervenes to defend and protect us, as our great and mighty Champion against the devil; so that by His prayer and fasting, even where ours falter and fail, He shields us by His grace and mercy and protection. Only let us avail ourselves daily of His Gospel, and thus find shelter in the shadow of His wings, a steady bulwark in the Mighty Fortress of His Church, and a most precious recourse in His gift of prayer. "O Lord, open my lips, and my mouth shall declare Your praise."