This is actually described on the wiki itself that the 'angels' are not really angels but manifestations of The Order and its beliefs. Combining Shintoism, Christanity, and Native American religous bases. So it is more safe to say that they are either demons, spirits, or hallucinations made real. This is due to the fact that The Order has very violent teachings and rituals, similar to the idea of demon worship. That's just my two cents, and may be wrong, but it does have a more demonic and punishing feel in the Otherworld then Heaven would feel like.
It's actually more the fact that the town of Silent Hill itself is built on sacred Native American trial grounds. Being native myself, i can explain that the land was meant to be used as a mirror of sorts as it will reflect what is in a person's heart or spirit. So with that being said. A person full of guilt and regret and malice, Obviously will see themselves in a nightmare of all of those things personified and put into symbolism, that at the same time sets them on a pathway that will help to make them understand, forgive, and better themselves (if they survive the "trial") so to speak. While a person pure of heart will only see the land for what it is. This also means that the town is not evil. or haunted at all... It just so happens that the stories in the games we see have to do with people with closets full of skeletons.