There are many reasons why God expressly and repeatedly warns us about the world and its wisdom?and to never compromise His Word, or compromise with the world. Ideas have consequences. The world's ideas always have dreadful consequences.
So, not only has the Church lost its saltiness and influence on the world, much of the Church has become like the world! Even worse, now many who claim Christ are actively opposed to the teachings of Christ, all in the name of Christ. And, consequently, this is doing significant damage to the world, including every non-believer.
"I believe that one reason why the church of God at this present moment has so little influence over the world is that the world has so much influence over the church", ~ C.H. Spurgeon