Warfare

The levites were not sacrificing priests, but they belonged to the same tribe as these, and they had sacred functions to discharge. So we come to this principle, that Christian service is to be looked at as warfare.
Now, that is a principle which ought to be applied to all Christians. For there is no such thing as designating a portion of Christ’s Church to service which others have not to perform. The distinction of “priest” and “layman” existed in the Old Testament; it does not exist under the New Covenant, And there is no obligation upon any one Christian man to devote himself for Christ’s sake to Christ’s service and man’s help (which is Christ’s service), that does not lie equally upon all Christian people. We, if we are Christian people at all, are all bound to do this work of “the tabernacle,” and war this warfare.
By “fighting the good fight of faith,” we generally mean our struggle with our own evils and with the things that hinder us from developing a Christlike character, and “growing in the grace and knowledge of our Lord and Savior Jesus Christ.” But this is about another sort of warfare, the warfare which every Christian man has to wage who flings himself into the work of diminishing the world’s miseries and sings, and tries to make people better, and happier because they are better. That is a fight, and will always be so, if rightly done. The foes are mountainous. Culture or society is built upon a non-Christian basis. There’s not one “Christian” nation on the face of the earth. So, every man that has come into personal touch with the Gospel of Jesus Christ, made Him Lord, and has felt that His commandments are the supreme authority in his own individual life, when he goes out into society, come full tilt against a whole host of things that are in pronounced antagonism, or in real though unacknowledged contradiction, to the principles by which a Christian has to live for himself, and to commend to his brethren. So we Christian men, as individuals, as members of a community and able to bring some influence to bear upon the conscience of society, have to fight against popular evils, and to war for righteousness’ sake.
The worst of all our foes, in doing Christian service, is our own miserable selves, with our laziness, and our vanity, and our wondering what A, B, and C will think about us, and the mingling of impure motives with nobler ones, and our being angry with people because they are so insensible, not so much to Christ’s love as to our words and pleadings. Unless we can purge all that devil’s leaven out of ourselves, we have little chance of working “the work of the tabernacle,” or warring the warfare of God.
Alexander Maclaren’s Library of Scripture Exposition. ch4, p301