A speech at a church anniversary should involve a retelling of the church's history and a celebration of the people who have played a special role at the church over the years. Incorporate input from other people who know a lot about the church or who have special gifts to help prepare a speech.
A church anniversary should involve telling the story of the church's history. Older members of the church are likely to be excited to tell their personal stories and may have some real insights on how the church developed. Check local newspapers for documentation of any key moments in the church's history. Include information regarding the construction and dedication of church buildings. Point out and celebrate any members who have been with the church since its founding or for a very long time.
Tie remarks about a church's anniversary around a central theme, perhaps one involving God's faithfulness, giving glory to God for the church, or gratitude to God. Use the gifts of other congregants to prepare a speech, asking good writers to contribute poetry or other elements of a speech.
Besides looking backward in time at a church anniversary, take a moment to speak about the church's future as well. Before speaking at the anniversary, seek out church members, and ask them their opinions about the future direction for the church, and then incorporate some of their ideas in any speech.