"... as the servants of Christ, doing the will of God from the heart" (Eph. 6:6).
And then the third quality of a creed that a man may keep up to the end is that it is a creed capable of being turned into action. A mere speculation, however true it be, I think you never can be sure that the mind will hold. The faith which you keep must be a faith that demands obedience, and you can keep it only by obeying it. Are not both of these true? Those parts of religion which are purely speculative, if indeed such mere speculation is part of religion at all, are the parts in which men most often and most easily change. A hundred men change their views of abstract truth for one who alters his conviction of practical duty. The one may be changed and nothing suffers; a change in the other alters the whole life.
Look at two men holding the same truth--the truth of the Trinity, for instance. To one it presents itself always as a doctrine to be learned, to the other as a law to be obeyed. One's view of it is always theoretical, the other's always practical. They both believe it, but one asserts it, demonstrates it, reasons about it. The other lives by it. Which is the true believer? I can conceive of the first man losing his belief and yet going on much the same. Convince him with a specious argument and he will let it drop, and, except that he talks of it no longer, nobody will know the difference. But take the truth of the Divine Father, the Divine Saviour, the Divine Comforter, out of the other's life, and all is gone. Duty no longer has a zest, nor prayer an object, nor grief a consolation. The whole life falls to pieces when its truth is gone. Is not this last the man who will keep the faith?