While I did draw inspiration from Christianity, this is not about the actual Christian religion. I just use the term "angel" because it helps to understand. In reality, those angels are more like "honorable dead lawyer-warriors".
In my story, there is a deity that is strictly a judge. He did not create the world. He does not pass judgment to people while they are still alive. Everyone goes to heaven, but the bad people have to go to some room of repent to think about the naughty things they did before they go to heaven.
So, what could be some reason that his most powerful believers could temporary summoned essentially his angels to weaken the believers' enemy and strengthen the believers' ally?
The current idea I have is that maybe the believers can only do it in the situation when the bad guys are doing something truly terrible, and the believers could summon angels to help the bad guys lessen their crime. (Essentially, the kind believers want to spare the bad guys from more time in the naughty room, which is why the believers will summon angels to help prevent the bad guys from succeeding at whatever they're doing).
It is very much like summoning a holy court, where the juries are the angels, the believers are accusers, etc. If the bad guys were judged guilty, then they will weaken by a certain amount. Not to the point where they can't fight, but it'd still give the believers advantage.
Is this a reasonable way to justify the presence of angels of a god who doesn't do anything to people until the after those people passed away? What more could I add to flesh out the concept more? Or is there a better way to do this?