I read or heard one time that a guy inquired if praying for the dead might do some good because God, who knows the future from eternity to the past, knew, before they died, you would pray for that person. I found this a very iffy concept. But the more I have thought about it, the more I have considered it possibly worthwhile to pray for the dead. God knew that prayer would be made from eternity to the past, before the prayed-for person was ever born. God is willing that none should perish but that all should come to repentance. Praying for the dead reminds God of that. I have heard it is reasonable to remind God of His promises.
Also, I sometimes pray for people whose death I will hear about in the future and will wish I had prayed for them while they were still alive. I am praying for any such, in advance of their death! I also pray for anybody, dead or alive, whom I will later wish I had prayed for them earlier. One time, after I started praying these kinds of things, I heard about a famous basketball player who died in a helicopter crash. There was a news report that he had received communion shortly before going on the helicopter ride. While it is probably not the case, it came across as if God was letting me know that my retro-prayers were answered!
Also, I sometimes pray for people whose death I will hear about in the future and will wish I had prayed for them while they were still alive. I am praying for any such, in advance of their death! I also pray for anybody, dead or alive, whom I will later wish I had prayed for them earlier. One time, after I started praying these kinds of things, I heard about a famous basketball player who died in a helicopter crash. There was a news report that he had received communion shortly before going on the helicopter ride. While it is probably not the case, it came across as if God was letting me know that my retro-prayers were answered!