Consider first, that in this spiritual warfare the Christian soldier must not only be furnished with arms of defence, such as breastplate, shield, and helmet, but he must also provide himself with a proper sword, with which he may be able to attack and to beat down the enemy. Now this sword of the spirit, or spiritual sword, to be employed in the Christian's conflict is, according to the apostle, the Word of God. The truths of God's heavenly word, heard from his ministers, or read in good books, and received as the seed of life, and laid up in the heart when embraced with a lively faith, and pondered at leisure by deep meditation, serve in a double capacity, both to defend us and to annoy the enemy; they are both a shield and a sword. They are a shield, because the continual remembrance of these great truths baffles and defeats all the temptations of the world, the flesh, and the devil; none of them have any force against a soul that daily meditates on God's holy Word and enters into the true spirit of it. And they are a sword too, which none of them all can withstand, when drawn against them by a lively faith; it attacks them whenever it meets them, and never fails of victory; it beats down all their fortifications, and forces them out of all their entrenchments. Such is the efficacy of daily meditation on divine truths: it roots out all vices, and establishes all virtues.
Consider 2ndly, that in the Christians' conflict this sword of the spirit is to be used, according to the apostle, in such manner as to be accompanied with all prayer and supplication, praying at all times in the spirit, and in the same watching with instance. From which words we gather the great importance, yea, the absolute necessity, of fervent prayer in this our spiritual warfare; and that, not only in the time of more dangerous and obstinate temptations, but as he says, at all times, and with instance. Oh! 'tis the want of observing this prescription makes so many shamefully yield in the time of temptation. And indeed we may say with absolute truth, that no one is ever overcome but for want of prayer; and that a neglect of prayer is the original cause of the fall of all them that fall from God by sin. For his infinite goodness never forsakes them that do not first forsake him; he never withdraws his grace from them that do not first withdraw themselves from his grace; he is faithful, and will not suffer us to be tempted above our strength, but will assuredly give us the victory if we always cast ourselves upon him by fervent and humble prayer.
Consider 3rdly, that the apostle prescribes to the Christian soldier, in order to overcome the enemy, to join watching with his prayer, agreeable to the doctrine of our redeemer; who on many occasions enjoins to all his followers a perpetual watchfulness; and in particular the night before his passions bid his disciples 'watch and pray, lest they should enter into temptation,' Matt. xxvi. 41, clearly intimating by these words, that our best and only security against being overcome by temptation, is to join watching with prayer, and to oppose these two against all our spiritual enemies; ever remembering, that though our spirit be willing the flesh is frail. And what makes this watching still more necessary, is the nature of this warfare in which we are engaged against these wicked spirits, who are continually laying ambushes for us, and use a thousand deceits to ensnare us, and oftener prevail by tricks and stratagems, or by coming upon us unawares, than by open assault.
Conclude to make proper use of these weapons prescribed by the apostle and by our Lord himself, by filing thy mind with the word and the truths of God, and by diligence in watching and praying, and all thy conflicts shall be crowned with victory.