Remember when websites used to have flash intros (frequently made in Adobe Flash)? Personally, I am glad when websites don't, and get straight to content. What about other websites that are purely flash like most restaurant or band websites? Flash enables a website to have rich dynamic content, however it also has several drawbacks. If you're considering creating a website that is based on Flash, I want you to be aware of several things.
First, a website that uses Flash heavily is not as easy to update or tweak as a website written in html. Also a Flash site is less accessible for handicapped visitors, like a blind person that needs to use a screen reader. It is harder for search engines to crawl it, leading to poor rankings in search results. Usually scroll bars and links look different than traditional html websites causing the visitors to have to learn a new way to browse a site.
A Flash website usually has less of a focus on content and instead focuses on design and appearance. Like I've said before content is king and the design should only frame the content. Even though a Flash website is able to have as much content as a traditional html website, from my experience, they usually do not.
If you do need a website with rich experiences or media look into html5 which enables you to do just as much as Flash, but is based on a web standard instead of Adobe's proprietary software. You can have a great site in Flash (albeit difficult and rare), but be aware of these drawbacks and consider them in your planning process.
If you're looking at starting a website for your church read this article to help get you started on the process. In the article I list several different sites and software that are more open and include almost limitless functionality.