Our pastor recently preached on Psalm 104 about the divine wisdom in God’s manifold works of creation. He said animals and plants are examples of God’s wisdom, so if we don’t treat them well, we are disrespecting God’s wisdom. He tried to say creation, like salvation, is all about grace, but it seems to me that environmental sermons are a bit fluffy and sermons instead should be about the gospel of the saving grace of Jesus.
You are certainly correct that the heart of the gospel is, as Colossians 1 puts it, that God in Christ was reconciling the world to himself through the cross. Further, this reconciling work is central to the message of the church. One would be concerned if, over time, that message was absent from the preaching of the church and sermons seemed to be just talks about contemporary issues.
There are several things to consider, however, regarding your pastor’s sermon on Psalm 104. First, in accepting the charge to be a minister of the Word, your pastor vowed to preach the whole counsel of God. Psalm 104 is a part of the counsel of God. It is, in fact, one of the most beautiful and profound of the creation psalms of the Old Testament.
Second, by mentioning the damage that humans cause to the earth and the dangers of extinction, the sermon identifies a brokenness that affects the world and requires the reconciling work of Christ. There is a valid connection between the divine wisdom of Psalm 104 and the reconciling Christ of Colossians 1.
Finally, keep in mind that saving grace isn’t the only kind of grace there is. “Grace” simply means a gift, and creation itself is a gift. As George Bernanos says at the end of his book Diary of a Country Priest, “Grace is everywhere.”