The question immediately arises as to whether truth here means objective truth--the truth of the Gospel, or subjective truth, or, as we are accustomed to say, truthfulness. It would seem that the former signification is rather included in the sword of the Spirit, which is the word of God, and it is best to regard the phrase with (literally "in") truth' here as having its ordinary meaning, of which we may take as examples the phrases,' the unleavened bread of sincerity and truth'; love rejoiceth not in unrighteousness, but rejoiceth with the truth'; whom I love in truth.' Absolute sincerity and transparent truthfulness may well be regarded as the girdle which encloses and keeps secure every other Christian grace and virtue.
We do not need to go far to find a slight tinge of unreality marring the Christian life: we have only to scrutinise our own experiences to detect some tendency to affectation, to saying a little more than is quite true, even in our sincerest worship. And we cannot but recognise that in all Christian communities there is present an element of conventionalism in their prayers, and that often the public expression of religious emotions goes far beyond the realities of feeling in the worshippers. In fact, terrible as the acknowledgment may be, we shall be blind if we do not recognise that the average Christianity of this day suffers from nothing more than it does from the lack of this transparent sincerity, and of absolute correspondence between inward fact and outward expression. Types of Christianity which make much of emotion are, of course, specially exposed to such a danger, but those which make least of it are not exempt, and we all need to lay to heart, far more seriously than we ordinarily do, that God' desires truth in the outward parts.' The sturdy English moralist who proclaimed' Clear your mind of cant' as the first condition of attaining wisdom, was not so very far from Paul's point of view in our text, but his exhortation covered but a small section of the Apostle's.
This absolute sincerity is hard to attain, and still harder to retain. Hideous as the fact of posing or attitudinising in our religion may be, it is one that comes very easily to us all, and, when it comes, spreads fast and spoils everything. Just as the legionary's armour was held in its place by the girdle, and if that worked loose or was carelessly fastened, the breastplate would be sure to get out of position, so all the subsequent graces largely depend for their vigorous exercise on the prime virtue of truthfulness. Righteousness and faith will be weakened by the fatal taint of insincerity, and, on the other hand, conscious truthfulness will give strength to the whole man. Braced up and concentrated, our powers for all service and for all conflict will be increased. The bond of perfectness' is, no doubt, Love,' but that perfect bond will not be worn by us, unless we have girded our loins with truthfulness.
It may be that in Paul's memory there is floating Isaiah's great vision of the Branch' out of the stock of Jesse, on whom the Spirit of the Lord was to rest, and on whom it was proclaimed that faithfulness (or as it is rendered in the Septuagint, by the same phrase which the Apostle here employs, in truth') was to be the girdle of his reins; but, at all events, that which the prophet saw to be in the ideal Messiah, the Apostle sees as essential to all the subjects of that King.