St. Paul says in Philippians 1:18, “What then? Only that in every way, whether in pretense or in truth, Christ is proclaimed; and in this I rejoice….”
Let’s first notice what he rejoices in and doesn’t rejoice in. As as been said before the Bible is written in exclusive language. In other words if it makes a statement the alternatives are not true. In Paul’s case here he is rejoicing singularly that Christ is preached. That would exclude any other message preached. Paul is Christ centered in all of his epistles.
The whole of the life of the Christian church exists because of Jesus Christ and it would not exist without Him. Thus evangelists preach Christ crucified and don’t preach other messages.
The second point is that fruitful evangelists understand the depth, implications and nuances of preaching Christ. Paul lays out some of this in the remainder of the chapter.
Since everything came into being by, through and for Him, He is our redeemer and judge then there are no other messages but Jesus Christ and Him crucified for our sins.