There's quite a difference between an apple that isn't edible and the poison berries of a thornbush - one is still fruit, the product of a heart pursuing after God, albeit in a fallen world. The other is a deception.
To some degree, we know this. We are willing to look past a few bad apples on a godly tree, so long as we can clearly see the godliness in that tree. For example, we may have a man in our church who looks at pornography, but he may also be a man who worships with all his heart, who leads prayer, who serves faithfully the church, who is involved in his family's life. And we might say that there is much we can learn from this man, so long as we pick only the good fruit. Or maybe we have a woman who is a gossip. But she is also what we might call a "Proverbs 31" woman, at least by the majority of her testimony. We may be willing to say that there is much we can learn from this woman, much that her spirit has to say to us. As long, of course, as we pick only the good fruit from her life and do not pick up on her gossip.
But at other times, we are not so gracious. Take this man or this woman, the same man and the same woman, the same largely godly example in their lives, but replace their sin with one that is more detestable to us, for whatever reason. Say that the man is a pedophile, and the woman is a lesbian. All of a sudden, we are no longer thinking about a few rotten apples.
These are thornbushes.
Why? Has the orientation of their hearts toward God changed? It has not. They still seek God with all that they are. The man still worships with all his heart, leads prayer, serves faithfully, is involved in his family's life. He just has a different vice of sin, one we find harder to love. How could anyone be a pedophile and a Christian? It just doesn't make sense to us. No, this is no longer a tree; it's a thornbush.
The woman is still a Proverbs 31 woman by so many accounts of the text. Her spirit declares exactly the same testimony as before. But now, she is a lesbian and not a gossip. How could anyone be a lesbian and a Christian? It just doesn't make sense to us. Now, she is a thornbush, and not a tree.
Has something about the nature of sin truly fundamentally changed the hearts of these persons among us? No. Not at all. What's happened is this:
We've decided we no longer care for the taste of apples.
That's all it is. It's not that all of a sudden, the apples are poison berries because the nature of sin is different. No, it's that all of a sudden, we look again at the tree and determine...we just don't like apples. But that doesn't make sense, does it? Of course we like apples! We just can't say that there is anything from this particular tree that we care for, but since this is an apple tree, we must either admit our prejudice against this one tree...or we must decide that we do not like apples.
We can do neither, so we call it a thornbush.
We're not really judging the tree by its fruit any more; we're judging its fruit according to our own taste. And we are wrong to do so.
Just because you cannot condone whatever sin someone is engaged in, just because you cannot understand or do not want to associate yourself with their lifestyle, you cannot write them off. You cannot burn down the orchard because you decide you don't like apples. For God, the message of fruit has always been about the fundamental nature of the heart, not the fruit. It's about the root system and how deep into the heart of creation the tree plants itself.
It's about whether this tree has been planted near streams of living water, is drawing from the life of God for its very breath, and is producing fruit at all - even if not every one is edible.
It's about the fundamental difference between a fruit tree and a thornbush. One is never capable of producing anything good; the other produces good in abundance, but still has a few bad ones thrown in.
It's fallen human nature. It's who we are.
And if all these rotten apples were really poison berries, we'd all be dead by now. But we're not. Because they're not. And as long as we keep pretending that they are, we are going to keep missing out on some amazing fruit that godly sinners have to offer us. Amazing, amazing fruit.
Even if you don't like apples.