Bavinck on Christian warfare
We may not be a sect. We may not want to be one, and we cannot be one, except by a denial of the absolute character of the truth. Indeed, the kingdom of heaven is not of this world. But it does demand that everything in this world serve it. It is exclusive and jealous, and it will indulge no independent or neutral kingdom of the world alongside of itself. Naturally, it would be much easier to leave this age to its own ways, and to seek our strength in a quiet withdrawal. No such rest, however, is permitted to us here. Because every creature is good, and nothing is to be refused, if it be received with thanksgiving, since all things are sanctified by the Word of God and prayer, therefore the rejection of any creature were ingratitude to God, a misjudgment or under-evaluation of His goodness and His gifts. Our warfare may be conducted against sin alone. No matter how complicated the relationships may be, therefore, in which the confessors of Christ are placed in this time, no matter how serious, difficult, and virtually insurmountable the social, political, and especially the scientific problems may be, it were faithlessness and weakness in us proudly to withdraw from the struggle, perhaps even under the guise of Christian motivation, and to reject the culture of the age as demonic.
— Herman Bavinck, Our Reasonable Faith, p. 10.