Ablaze! proponents like to quote C.F.W. Walther when he speaks with zeal and fervor about missions. Good on them.
But they are rather selective in their choice of quotes and do not give both sides of the issues. For example, Ablaze! advocates are generally not too enthused about the topic of "pure doctrine," hurling diatribes against "incessant internal purification."
Still, for every fervent Walther mission citation, I think I could find five zealous "pure doctrine" quotes like the following:
“It is true, brethren, as you well know, that in our day it is common for people to say, ‘Emphasizing doctrine so much only harms and hinders the kingdom of God, yes, even destroys it.’ Many say, ‘Instead of disputing over doctrine so much, we should much rather be concerned with souls and with leading them to Christ.’ But all who speak in this way do not really know what they are saying or what they are doing.” Our Common Task - The Saving of Souls, (1872).
“Nowadays any one who insists that pure doctrine is a very important matter is at once suspected of not having the right Christian spirit. The very term ‘pure doctrine’ has been proscribed and outlawed. Even such modern theologians as wish to be numbered with the confessionalists, as a rule, speak of pure doctrine only in derisive terms, treating it as the shibboleth of dead-letter theology. If any one goes to the extreme, as it is held to be, of even fighting for the pure doctrine and opposing every false doctrine, he is set down as a heartless and unloving fanatic. What may be the reason? Unquestionably this, that modern theologians know full well that they have not that doctrine which in all ages has been called, and verily is, the pure doctrine. Furthermore, they even think that pure doctrine does not exist (is a non-ens), except in a dream world, in the realm of ideals, in the Republic of Plato. (Law and Gospel, 347)
“How foolish it is, yea, what an awful delusion has taken hold upon so many men's minds who ridicule the pure doctrine and say to us: ‘Ah, do cease clamoring, Pure doctrine! Pure doctrine! That can only land you in dead orthodoxy. Pay more attention to pure life, and you will raise a growth of genuine Christianity.’ That is exactly like saying to a farmer: ‘Do not worry forever about good seed; worry about good fruits.’ Is not a farmer properly concerned about good fruit when he is solicitous about getting good seed? Just so, a concern about pure doctrine is the proper concern about genuine Christianity and a sincere Christian life. False doctrine is noxious seed, sown by the enemy to produce a progeny of wickedness. The pure doctrine is wheat-seed; from it spring the children of the Kingdom, who even in the present life belong in the kingdom of Jesus Christ and in the life to come will be received into the Kingdom of Glory. May God even now implant in your hearts a great fear, yea, a real abhorrence, of false doctrine! May He graciously give you a holy desire for the pure, saving truth, revealed by God Himself!” (Law and Gospel)
Want to talk about mission zeal? Great. I'm all for it. But let's do with with pure doctrine. It's what our Lord expects.