You ask prayer that the landlord give his life to the Lord Jesus so as not to lose it. The verse you cite, that whoever loses his life for Christ will save it, points to a profound death: the dying to self, to worldly care, to softness, to the darkness that blinds the soul. But this loss is not first inflicted from without by our declarations of victory over a rented apartment; it begins within, when the eye of the soul is made single and full of light.
What is the eye of the soul but the mind? If the mind is darkened by error, the whole life is darkness, however much we may speak of light and power. You desire your landlord to see the Greatness and Power of the Lord; this is good. But learn how that light shines. It is not by our shouting down the darkness as if we commanded it, but by our becoming light ourselves. For the Lord said, “Ye are the light of the world.” And the light reproves the darkness not by mere words, but by exposing the hidden things through a virtuous and conspicuous life. When your conduct is irreproachable, manifest as light, then the sin of another, brought to light, may become light to him, not the sin itself, but the sinner, when he is admonished and repents and obtains pardon. That is the true victory, not one obtained by doing harm or talking of unclean spirits as if they were to be driven out by our own authority, but by suffering wrong, by bearing the cross.
Consider: the cross is our symbol of victory. Everywhere we inscribe it, on our forehead, on our mind, because by it all things are wrought. Christ’s victory came through losing His life, through not accepting deliverance that He might obtain a better resurrection. He delivered us from error and dissolved mental darkness by His own death. So if you want your landlord to gain that salvation, do not put your trust in a prayer that simply declares what you wish to be true about a rented apartment. Instead, be careful to hear the word yourself, and to cultivate a continual recollection of it. No one part is sufficient for our salvation; there must be careful hearing, fortitude, contempt of riches, and deliverance from all worldly things. Then, bearing about the dying of the Lord, your life will shine.
The landlord will not give his life to Christ because we declare victory over darkness in his journey; he will give his life when he sees the light of good works, when the gospel is sown in his heart with patient hearing, and when the Cross is lifted up, drawing all men. Pray, then, that God’s mercy and grace open his eyes, that the light of the knowledge of the glory of God in the face of Christ may expel his inner darkness. Pray also that you yourself may be preserved from the vain imagination that by speaking of power you can force a soul into the kingdom. The way is narrow: it is to lose everything, even one’s desire to control the outcome, and to trust the God who is righteous, who cannot be unrighteous, and who gives the victory not as men reckon it. That victory is to shine forth in His kingdom, having died here on account of it. So let your prayer be humble, and let your life be a lamp. Then, if it be God’s will, the one who stumbles in darkness may yet see and live.