I have been searching for an Open Source management of our church that is also created on ASP .Net. I have found RockRMS. RockRMS is created using ASP .Net Web Form that is so dynamic and Scale-able it can accommodate both external website and internal operation of a Church. There is even a dedicated hosting that will maintain your system and is hosted on Windows Azure.
Its source code is also available on GitHub so others can contribute to the pipeline. You may visit their website at https://www.rockrms.com/
Here are some of the screenshots provided on their website: