Early on in Piper’s pastorate, he articulated some theological reasons for having church picnics:
If picnics don’t have to do with God we may as well close up shop. Either all we do has to do with God or he is not God. “Whether you eat or drink, or whatever you do (like picnics), do all to the glory of God” (1 Corinthians 10:31).
Here are his main points:
Meeting as a church out-of-doors is an affirmation and celebration of God as creator of the world;
Informal togetherness, especially involving recreation, cultivates the unity of God’s people, which we are commanded to maintain (Ephesians 4:3);
A leisurely afternoon together affirms the need for rest and re-creation.
Read Piper’s article “Toward a Theology of Church Picnics.”