How Can Christians Be Meek and War-like at the Same Time?

In discussing the sixth sign of authentic spiritual affections, Jonathan Edwards poses this objection. After arguing that true godly experience results in meekness, gentleness, lowliness of spirit, he says--

But here some may be ready to say, Is there no such thing as Christian fortitude, and boldness for Christ, being good soldiers in the Christian warfare, and coming out bold against the enemies of Christ and his people?

Edwards responds:

To which I answer, There doubtless is such a thing. The whole Christian life is compared to a warfare, and fitly so. And the most eminent Christians are the best soldiers, endowed with the greatest degrees of Christian fortitude. And it is the duty of God's people to be steadfast, and vigorous in their opposition to the designs and ways of such, as are endeavoring to overthrow the kingdom of Christ, and the interest of religion.

But yet many persons seem to be quite mistaken concerning the nature of Christian fortitude. 'Tis an exceeding diverse thing from a brutal fierceness, or the boldness of beasts of prey.

True Christian fortitude consists in strength of mind, through grace, exerted in two things; in ruling and suppressing the evil, and unruly passions and affections of the mind; and in steadfastly and freely exerting, and following good affections and dispositions, without being hindered by sinful fear, or the opposition of enemies. . . .

Though Christian fortitude appears, in withstanding and counteracting the enemies that are without us; yet it much more appears, in resisting and suppressing the enemies that are within us; because they are our worst and strongest enemies, and have greatest advantage against us. The strength of the good soldier of Jesus Christ, appears in nothing more, than in steadfastly maintaining the holy calm, meekness, sweetness, and benevolence of his mind, amidst all the storms, injuries, strange behavior, and surprising acts and events of this evil and unreasonable world. The Scripture seems to intimate that true fortitude consists chiefly in this, Prov 16:32. 'He that is slow to anger, is better than the mighty; and he that ruleth his spirit, than he that taketh a city.'

--Jonathan Edwards, Religious Affections, Yale ed., p. 350

Are we to be violent, war-like? Yes--against our own sin. The result is true meekness.
Dane Ortlund