Note, then, how to get at it. 'They that wait upon the Lord' is Old Testament dialect for what in New Testament phraseology is meant by 'Believe on the Lord Jesus Christ.' For the notion expressed here by 'waiting' is that of expectant dependence, and the New Testament 'faith' is the very same in its attitude of expectant dependence, while the object of the Old Testament 'waiting,' Jehovah, is identical with the object of the New Testament faith, which fastens on God manifest in the flesh, the Man Jesus Christ.
Therefore, I am not diverting the language of my text from its true meaning, but simply opening its depth, when I say that the condition of the inflow of this unwearied and immortal life into our poor, fainting, dying humanity is simply the trust in Jesus Christ the Redeemer of our souls. True, the revelation has advanced; the contents of that which we grasp are more developed and articulate, blessed be God! True, we know more about Jehovah, when we see Him in Jesus Christ, than Isaiah did. True, we have to trust in Him as dying on the Cross for our salvation and as the pattern and example in His humanity of all nobleness and beauty of life for young or old, but the Christ is the 'same yesterday, and to-day, and for ever.' And the faith that knit the furthest back of the saints of old to the Jehovah, whom they dimly knew, is in essence identical with the faith that binds my poor sinful heart to the Christ that died and that lives for my redemption and salvation. So, dear brethren, here is the simple old message for each of you, young or old. No matter where we stand on the course of life, there may come into our hearts a Divine Indweller, who laughs at weariness and knows nothing of decay; and He will come if, as sinful men, we turn ourselves to that dear Lord, who fainted and was weary many a time in His humanity, and who now lives, the 'strong Son of God, immortal love,' to make us partakers in His immortality and His strength. The way, then, by which we get this divine gift is by faith in Jesus Christ, which is the expansion, as it was the root, of trust in Jehovah.
Further, what is this strength that we thus get, if we will, by faith? It is the true entrance into our souls of a divine life. God in His Son will come to us, according to His own gracious and profound promise: 'If any man open the door I will enter in.' He will come into our hearts and abide there. He will give to us a life derived from, and therefore, kindred with, His own. And in that connection it is very striking to notice how the prophet, in the context, reiterates these two words, _'fainteth_ not, neither is _weary._' He begins by speaking of 'God, the Lord, the Creator of the ends of the earth, who fainteth not, neither is weary.' He passes on to speak of His gift of power to the faint. He returns to the contrast between the Creator's incorruptible strength and the fleeting power of the strongest and youngest. And then he crowns all with the thought that the same characteristics will mark them in whom the unwearied God dwells, as mark Him. We too, like Him, if we have Christ in our hearts by faith, will share, in some fashion and degree, in His wondrous prerogative of unwearied strength.
So, brethren, here is the promise. God will give Himself to you, and in the very heart of your decaying nature will plant the seed of an immortal being which shall, like His own, shake off fatigue from the limbs, and never tend to dissolution or an end. The life of nature dies by living; the life of grace, which may belong to us all, lives by living, and lives evermore thereby. And so that life is continuous and progressive, with no tendency to decay, nor term to its being. 'The path of the just is as the shining light that shineth more and more,' until it riseth to the zenith of the noontide of the day. Each of you, looking forward to the certain ebbing away of creatural power, to the certain changes that will pass upon you, may say, 'I know that I shall have to leave behind me my present youthful strength, my unworn freshness, my buoyancy, my confidence, my wonder, my hope; but I shall carry my Christ; and in Him I shall possess the secret of an immortal youth.'