First, lets address what’s right with it. What it seems to be advocating is Christian witness. Yes, we are to be the light of the world, the salt of the earth. We should be holy as our Heavenly Father is holy. We should love others in a way that displays the love of Christ. So, yes, that’s absolutely true.
But Christian witness and preaching the gospel are not the same thing, and they should accompany one another. Preaching the gospel requires words. The gospel has factual content, content that people need to know in order to be right with God. The gospel is that while we were sinners, at enmity with God and deserving of eternal and infinite suffering, God gave His only Son to die on the cross, taking on the punishment that sinners like you and me deserve. And this Savior Jesus rose from the grave, victorious over sin and death, and if you trust in Him for your salvation, you will have your guilt removed from you, and you will enjoy Him forever. That’s the gospel. That’s the good news. And you can’t mime it with your good works. You must share it.
So, in conclusion, serve God and people with your heads, hearts, and hands, and share the gospel with your mouths.