Being confident of this very thing, that he which has begun a good work in you will perform it until the day of Jesus Christ:
If any of you should be well assured that, in a certain line of business, you would make a vast sum of money, would that confidence lead you to refuse that business, would it lead you to lie in bed all day, or to desert your post altogether? No, the assurance that you would be diligent and would prosper would make you diligent. I will borrow a metaphor from the revelries of the season, such as Paul aforetime borrowed from the games of Greece — if any rider at the races should be confident that he was destined to win, would that make him slacken speed? Napoleon believed himself to be the child of destiny, did that freeze his energies? To show you that the certainty of a thing does not hinder a man from striving after it, but rather quickens him, I will give you an anecdote of myself: it happened to me when I was but a child of some ten years of age, or less. Mr. Richard Knill, of happy and glorious memory, an earnest worker for Christ, felt moved, I know not why, to take me on his knee, at my grandfather's house, and to utter words like these, which were treasured up by the family, and by myself especially, "This child," said he, "will preach the gospel, and he will preach it to the largest congregations of our times." I believed his prophecy, and my standing here today is partly occasioned by such belief. It did not hinder me in my diligence in seeking to. educate myself because I believed I was destined to preach the gospel to large congregations; not at all, but the prophecy helped forward its own fulfilment; and I prayed, and sought, and strove, always having this Star of Bethlehem before me, that the day should come when I should preach the gospel. Even so the belief that we shall one day be perfect, never hinders any true believer from diligence, but is the highest possible incentive to make a man struggle with the corruptions of the flesh, and seek to persevere according to God's promise.
(C. H. Spurgeon.)
Parallel VersesKJV: Being confident of this very thing, that he which hath begun a good work in you will perform it until the day of Jesus Christ: