I. The confession and rebuke of St. Peter seem to be closely connected with the solemn teaching of the text. The fearfully wrong view which St. Peter had taken of what was consistent with the character and office of our Lord, notwithstanding the wonderful revelation he had received concerning His true being; seems to have suggested, as it were, to our blessed Lord the necessity of publishing clearly and broadly certain essential laws of His kingdom. So He called to Him the people with His disciples also; for the lesson He was about to teach was one for all ears, it could not be too extensively known nor too carefully pondered; and when He had called them He said, "Whosoever will come after Me, let him deny himself, and take up his cross, and follow Me." Thus He laid down self-denial as the basis of His service. He did not wish any one to follow Him under false notions. As it followed, that becauseHe was Christ, thereforeHe must suffer, so it followed that those who would be great in His kingdom must obtain their position, not according to the fashion of this world, but by denying themselves and taking up the cross.
II. To those whom Christ immediately addressed, and those of the times immediately following, these words would be a tower of strength; and even to ourselves, they are very far from useless, if they teach us that no real happiness can be gained by shrinking from Christ's yoke, and that all that we can do for Christ and all that we give up for Him, and, if need be, all that we suffer for Him, will be richly rewarded by Him whom we serve. We learn from the text that an earnest Christian life requires the sacrifice of everything which may be a hindrance to its growth; even a man's life must be jeopardised for that which is his true life, and the gain of all things will be an infinite loss if it entail the sacrifice of our spiritual life. The world is a great prize, judging according to human estimates. It includes all the wealth, the power, the pleasures that human nature is capable of possessing and enjoying; yet what is it, if the man who has gained it has lost himself? its enjoyment can only last for an hour, and the joys of heaven last for evermore.
Bishop Harvey Goodwin, Parish Sermons,2nd series, p. 278.
Reference: Mark 8:35. S. A. Brooke, Christian World Pulpit,vol. xv., p. 392.