It was the duty and responsibility of the Christian Church to define sin. However, the Christian Church has long since been upstaged by Christ-haters and their followers. Now it is Christ-haters who define sin here in the Western and American Babylon-Egypt-Sodom and Gomorrah. And they use broken, perverted law to punish the 'wicked,' meaning those who don't use preferred pronouns, refuse to bake cakes for 'gay' marriages, protest choice (death of unborn and already born) and support the great evil--life, don't believe in global climate change, and so on.
This is where things stand today, and yes, our Lord and Savior will have the last word.