we weren't really sure what to do for a service, since he hadn't been a churchgoer in ages (raised Episcopalian, later UCC when we were kids, but no noticeable religion in at least 30 years). He had been living at a senior apartment complex affiliated with the Lutheran church (ELCA), so we contacted the Lutheran pastor who was the chaplain there. We explained to her that as far as we could tell Dad had been pretty much an agnostic, which didn't bother her (she said God loves you even if you don't believe in him), and we left it up to her to come up with an appropriate service. Most of his friends who would be coming to the service were Lutheran anyhow, and we knew Dad probably wouldn't care. So the pastor asked us to write out some memories which she read, and added a short homily and a few prayers. The music was classical because that's what Dad liked. Since funerals are really for the living, anything that your Dad would have been OK with and that comforts the survivors will be a good service. My condolences for your loss.