Only when those same stones might be used to build something. That is to say, only when it might be helpful.
It seems to me there is no good reason for us to get on a pedestal to throw stones at other Christians in the presence of people who we know will simply agree with us, laugh, and applaud. I don't see any benefit of Christians saying, "Yeah, look at us, aren't we're so stupid?" other than perhaps to appear cool and self-critical. Simply put, we don't need Christians (particularly evangelicals) mocking all the stupid things evangelical Christians do and say. We have an entire unbelieving, fallen world to do that job for us. We don't need to help them.
There are other more pressing things Christians can be doing than pointing and laughing at every foolish thing evangelicals do. As Proverbs 26:4 says, "Answer not a fool according to his folly, lest you be like him yourself." We as Christians have an urgent mission to complete, and those Christians who are blessed to possess more understanding or knowledge should not waste time proving how funny or clever we are by playing whack-a-mole with every stupid idea that evangelicals believe. We'll never get around to doing real kingdom work.
The truth is it's incredibly easy to jump on every single foolish thing a Christian does, but it is also immature. It's like the third grader who looks for every opportunity to tease his brother in preschool who still thinks 2+2=5. It takes a loving brother to show his younger sibling the error of his ways, and not laugh at him. And it takes patience and courage to come along side and correct our fellow brothers and sisters when they are mistaken.
So what we do need is Christians to recognize the areas in which their fellow family members are ignorant or misguided, and speak to them with boldness and kindness to correct them, and not mock them. What good is it to the person who doesn't realize his mistake if all you do is mock and laugh at his stupidity? Aren't you all the more foolish if you know the truth but don't share it with others?
Shortly after the admonition in Proverbs 26:4, the same chapter says, "Answer a fool according to his folly, lest he be wise in his own eyes."
As Christians we should seek discernment to navigate when it is appropriate to disengage with the foolish Christian, and when to engage, and if we do, that we do so to lovingly correct them and not mock them.
(In response to all this, some might be thinking, "Aren't you just throwing stones at Christians who throw stones?" And the answer is: Maybe...but I hope I am doing it in a way that builds something.)
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