While there are not many poems written specifically for a church's anniversary, there are many written about religion. One poem is "The Spirit Filled the Church," by Judy Crowe, with lines such as, "The Spirit filled church is the Lord's church, And is always faithful to do the Lord's will."
One poem that talks about the mission of a church in spreading the word of God to the community and world is "Sent Out," by Judy Crowe. In it, she talks about how individuals are called to different paths by God to spread the word of the Bible. It could be appropriate for a church anniversary in that it explores the function of the individual members of the church, so a person could focus on the church being a community of people called to different ways of spreading God's word.
Another poem by Judy Crowe is "Love Remains." This poem discusses the idea that God teaches people to use love to find the joy in their lives, and although trials may come up that test the happiness of each individual, that if they rely on God that they will continue to live in a joyful state of mind. This poem could help members of a church celebrate a church anniversary because it highlights an important aspect of why people seek out churches.