As is usually the case, there are ranges on a spectrum when it comes to the question of whether believers should speak and live in such a way that unbelievers would be attracted to the gospel of Christ.
There is one side—usually driven by the Bible and theology, even Reformed, Calvinistic doctrines such as the depravity of man and the need for irresistible grace—of those who argue that Christians and the gospel cannot be attractive to sinners and therefore any attempt to make ourselves winsome is naive at best and probably actually dangerous, you know, slippery slope and all.
On the other side—sometimes driven by the apparent callousness and unloving nature of the Bible-theology folks, and/or sometimes driven by the apparent gravity of Jesus demonstrated in the Gospels—are those who maintain that Christians and the gospel can be attractive to sinners and therefore any refusal to make ourselves winsome is at best immature and probably actually ungodly.
I am a truth guy. I think the Bible is the ultimate standard. My wife and I named our only son Calvin. I have served my time in very man-centered churches and can see with my eyes how compromised much of the Christian message is today because of those who try to win the world by being like it. One of my favorite books ever is Ashamed of the Gospel by John MacArthur, and I read it at a time when I was first learning the doctrines of grace. His book gave me categories to resist pragmatism along with the heroic narrative and quotability of Charles Spurgeon.
However, Solomon said it was worth gaining wisdom in order to increase persuasiveness of speech (Proverbs 16:21; 16:23). Wisdom works to be winsome. Paul told the Cretan slaves that they should “adorn the doctrine of God our Savior“ in their behavior (Titus 2:10), not on their book selling tours. Adorning makes it look good, appealing, desirable. Paul also said that “we are the aroma of Christ to God among those who are being saved and among those who are perishing, to one a fragrance from death to death, to the other a fragrance from life to life” (2 Corinthians 5:15-16). Speaking about Christ and living lives for Christ is a smell, detestable to some and delightful to others. Don’t we want it to be delightful? And when does the delightful, life to life part start? Only after a man believes, or as God’s Spirit is sovereignly drawing him to believe?
Of course if no one can hate what we’re doing, we may be seeking the wrong kind of attractiveness. Do not be ashamed of the gospel, and don’t be conformed to this world. But if no one wants what we have, we may be an ungodly sort of unattractive. Life can smell like death to the dead, but deadness also smells like death to the dead.