Was because decades ago and beyond Western culture was “churched.” People were familiar with Jesus and world religions were just that – out in the rest of the world. Our Western religious homogeneity had us taking faith three steps ahead because we agreed on Jesus with those we were trying to convert. What we disagreed on was “church” doctrine and practice.
Jesus gives us a line or two on “ekklesia” or church, first in talking about it when he said upon this rock I will build my church and second in Matthew 18 on reconciliation among believers. That is all Jesus had to say directly on church.
So our evangelism skipped Jesus to get to the man who instructs us on church (Paul) and the book that describes the activity of the first Christians (Acts).
Now we live in a world of unchurched, dechurched, nones and agnostics. You don’t bring them to Jesus through Paul. You bring them to Jesus through Jesus and use Paul for support.
It has always been Jesus first, church second but the Jesus part used to be presupposed. As we reach out to people we must expose them to the whole of inspired scripture and especially (at first) the gospels.
The world has changed and it pays to pay attention and adjust accordingly.