From the experience which Paul had in these various circumstances of life, he comes here to the general conclusion that he could "do all things." He could bear any trial, perform any duty, subdue any evil propensity of his nature, and meet all the temptations incident to any condition of prosperity or adversity. His own experience in the various changes of life had warranted him in arriving at this conclusion; and he now expresses the firm confidence that nothing would be required of him which he would not be able to perform. In Paul, this declaration was not a vain self-reliance, nor was it the mere result of his former experience. He knew well where the strength was to be obtained by which to do all things, and on that arm that was able to uphold him he confidently relied.
Remember, it is not hasty reading but serious meditating upon holy and heavenly truths that make them prove sweet and profitable to the soul. It is not he who reads most but he who meditates most who will prove choicest, sweetest, wisest, and strongest Christian.
For in him dwelleth all the fulness of the Godhead bodily. And ye are complete in him, which is the head of all principality and power: Colossians 2:9-10
And Hezekiah prayed before the Lord, and said, O Lord God of Israel, which dwellest between the cherubims, thou art the God, even thou alone, of all the kingdoms of the earth; thou hast made heaven and earth. 2 Kings 19:15
The phrase of standing at the door may be expressive of the near approach, or sudden coming of Christ to judgment, see James 5:9; and his knocking may signify the notice that will be given of it, by some of the immediate forerunners and signs of his coming; which yet will be observed but by a few, such a general sleepiness will have seized all professors of religion; and particularly may intend the midnight cry, which will, in its issue, rouse them all:
if any man hear my voice; in the appearances of things and providences in the world:
and open the door; or show a readiness for the coming of Christ, look and wait for it, and be like such that will receive him with a welcome:
I will come unto him, and sup with him, and he with me; to and among these will Christ appear when he comes in person; and these being like wise virgins, ready, having his grace in their hearts, and his righteousness upon them, he will take them at once into the marriage chamber, and shut the door upon the rest; when they shall enjoy a thousand years communion with him in person here on earth; when the Lamb on the throne will feed them with the fruit of the tree of life, and lead them to fountains of living water, and his tabernacle shall be among them.
Ah Lord God! behold, thou hast made the heaven and the earth by thy great power and stretched out arm, and there is nothing too hard for thee: Jeremiah 32:17
Now unto him that is able to do exceeding abundantly above all that we ask or think, according to the power that worketh in us, Unto him be glory in the church by Christ Jesus throughout all ages, world without end. Amen. Ephesians 3:20-21
Before the mountains were brought forth, or ever thou hadst formed the earth and the world, even from everlasting to everlasting, thou art God. Psalm 90:2