False doctrines are often allowed to infest our churches and families without an effort to correct them. True Christians often look on and content themselves with wishing it was not so. Here is no zeal for Christ! Do you think the Apostles would not have spoken out? We know they would! According to J. C. Ryle:
“It is always good to be zealous in a good cause.” (Galatians 4:18)
There is a generation in these days, which makes an idol of what it is pleased to call “earnestness” [sincerity] in religion. These men will allow no fault to be found with a [sincere] “earnest man.” Whatever his theological opinions may be – if he be but an earnest man, that is enough for these people, and we are to ask no more. They tell you we have nothing to do with minute points of doctrine, and with questions of words and names, about which Christians are not agreed. Is the man an earnest man? If he is, we ought to be satisfied. Earnestness [sincerity] in their eyes covers over a multitude of sins. I warn you solemnly to beware of this specious doctrine. In the name of the Gospel, and in the name of the Bible, I enter my protest against the theory, that mere earnestness can make a man a truly zealous and pious man in the sight of God.
These idolaters of earnestness would make out that God has given us no standard of truth and error, or that the true standard, the Bible, is so obscure, that no man can find out what truth is by simply going to it. They pour contempt upon the Word, the written Word, and therefore they must be wrong.
These idolaters of earnestness would make us condemn every witness for the truth, and every opponent of false teaching, from the time of the Lord Jesus down to this day. The Scribes and Pharisees were in earnest, and yet our Lord opposed them. And shall we dare even to hint a suspicion that they ought to have been let alone? … Devil-worshipers and idolaters at this day are in earnest, and yet our missionaries labor to expose their errors. And shall we dare to say that earnestness [sincerity] would take them to heaven, and that missionaries to heathen … had better stay at home? Are we really going to admit that the Bible does not show us what truth is? Are we really going to put a mere vague thing called “earnestness,” in the place of Christ, and to maintain that no earnest man can be wrong? God forbid that we should give place to such doctrine! I shrink with horror from such theology. I warn you solemnly to beware of being carried away by it, for it is common and most seductive in this day. … Admire zeal. Seek after zeal. Encourage zeal. But see that your own zeal be true. See that the zeal, which you admire in others, be a zeal “according to knowledge,” – a zeal from right motives – a zeal that can bring chapter and verse out of the Bible for its foundation. Any zeal but this is but a false fire. It is not lighted by the Holy Spirit. (“Be Zealous”)