The only way to get the recording is in the course of a lawsuit: only in a lawsuit can you compel the production of documentation (including recordings). If you believe you were terminated improperly and sue for that, or believe you have some other cause of action against the church, you can file a lawsuit against the church and in the lawsuit, use the legal mechanisms of "discovery" to get information and evidence from the other side and its agents or representatives (such as the elder). Unfortunately, this means you have to sue before having the recording and knowing if it supports your claim; and if don't want to sue or dont' have a viable claim against them, you will be unable to get it.