I'm sorry to have to be the one to tell you this, but "die" is exactly the same as "put into a graveyard from play" -- Dictate of Erebos is Better in decks that are not heavy black due to its cost being one more forgiving in the early game. That Flash is a great one.

Don't make the mistake of assuming that cards will never go to your grave with Athreos on the field. Imagine playing another Black deck that has some combination of Blood Artist, Falkenrath Noble, Deathgreeter, and Sangromancer on the field.

The point of these cards isn't just to maximize death triggers, it's also to encourage people to make the right choice -- to return the apostles to your hand.

Remembrance is perfect to this end. Each creature that your opponents do choose to put into your grave (for the sake of keeping you below 6 apostles, or for the sake of ending your Phyrexian Altar combo) will replace itself with another apostle from your library.

Ehem... WHY AREN'T YOU RUNNING ALTARS??

The cost is to sacrifice a creature, so you get the mana no matter what, and in the case of Phyrexian Altar, eventually your opponent must pay to put the creature into graveyard...

Which reminds me... you still haven't added Tendrils of Agony, when you have two perfect storm combos for this deck: Thrumming Stone, Phyrexian Altar or Phyrexian Altar and Remembrance together

To be honest, I am no where near owning this deck on paper so I've been really neglectful of it haha. I haven't been playing much MTG lately at all.

Sorry for the extremely late response. When I get some time I'm gonna revamp the list and see where it goes.