Do not be ashamed of the testimony about our Lord, nor of me His prisoner, but share in suffering for the gospel by the power of God. (2 Timothy 1:8 ESV)
That which represents the testimony in its fullest and closest approximation to the ultimate purpose of God, then has to be shorn of much that has been good, necessary, and of God in a preparatory way, and must be shut up to what is ultimate. The captivity is not to a conceived truth or a superimposed doctrinal acceptance. It is wrought into the very fiber of the being by experience following revelation, and revelation interpreting experience. It is not the championing of some espoused interpretation: it is that it is the very Life of instruments and the instrument is that in its very being. It is not a matter of wanting to be or not wanting to be, but cannot be other, a prisoner, the sovereignty of God has done it.
This applied both to Paul and to those who were brought into touch with him. For the Apostle the settling in to the sovereign ordering of God in his imprisonment issued in increasing illumination leading to spiritual emancipation. No one can fail to recognize the tremendous enrichment of ministry as contained in what are called "the Prison Epistles." If he had been restive, piqued, rebellious, or bitter, there would have been no open heaven, and a spirit of controversy with the Lord would have closed and bolted the door to the fuller Divine unveilings and clarifyings. When all was accepted according to the mind of the Lord, then "the heavenly places" became the eternal expanses of his walking about, and earthly bondage gave place to heavenly freedom. So it must be with every instrument set apart in relation to the higher interests of the Lord's testimony.