When we throw a stone up, it ascends until the moment when the propelling force ceases to be effectual. So long as this force acts, the stone travels higher and higher in its ascent, overcoming the force of the earth’s gravity. But when this force is sspent and ceases to act, then, as you know, the stone does not remain suspended in the air. Immediately, it begins to fall, and the further it falls the greater the speed of its fall. This, solely according to the physical laws of terrestrial gravity.
So it is also in the spiritual life. As a Christian gradually ascends, the force of spiritual and ascetical labours lifts him on high. Our Lord Jesus Christ said: “Strive to enter in through the narrow gate.” That is, the Christian ought to be an ascetic. Not only the monastic, but every Christian. He must take pains for his soul and his life. He must direct his life on the Christian path, and purge his soul of all filth and impurity.
Now, if the Christian, who is ascending upon this ladder of spiritual perfection by his struggles and ascetic labours, ceases from this work and ascetic toil, his soul will not remain in its former condition; but, like the stone, it will fall to the earth. More and more quickly will it drop until, finally, if the man does not come to his senses, it will cast him down into the very abyss of Hell.
It is necessary to remember this. People forget that the path of Christianity is indeed an ascetical labour. Last Sunday, we heard how the Lord said: “He that would come after Me, let him take up his cross, deny himself, and follow Me.” The Lord said this with the greatest emphasis. Therefore, the Christian must be one who takes up his cross, and his life, likewise, must be an ascetic labour of bearing that cross. Whatever the outward circumstance of his life, be he monk or layman, it is of no consequence. In either case, if he does not force himself to mount upwards, then, of a certainty, he will fall lower and lower.
Excerpt from a sermon of Metropolitan Philaret of New York (†1985), given on the Fourth Sunday of Lent, the Sunday of St John of the Ladder. From the beautiful edition of The Ladder of Divine Ascent published by Holy Transfiguration Monastery of Brookline, Massachusetts, page xxxii.