As long as your devotion to white and black is less than seven, Athreos isn't a creature.
Whenever another creature you own dies, return it to your hand unless target opponent pays 3 life.
4/26/2014 You are a creature’s owner if the card representing it began the game in your deck, or if it’s a token that entered the battlefield under your control.
4/26/2014 Athreos’s last ability will trigger if a token creature you own dies. The target opponent has the option to pay 3 life, although the token can’t return to your hand.
4/26/2014 It doesn’t matter who controlled the creature when it died. Athreos’s last ability will trigger if you owned that creature.
4/26/2014 The target opponent chooses whether to pay 3 life when Athreos’s last ability resolves. You won’t return the card to your hand if that player pays 3 life or if the card leaves the graveyard before the ability resolves.
4/26/2014 If there are no legal targets for Athreos’s last ability (perhaps because each of your opponents has hexproof), it will be removed from the stack with no effect. No one may pay 3 life and you won’t return the creature card to your hand.
4/26/2014 The type-changing ability that can make the God not be a creature functions only on the battlefield. It’s always a creature card in other zones, regardless of your devotion to its color.
4/26/2014 If a God enters the battlefield, your devotion to its color (including the mana symbols in the mana cost of the God itself) will determine if a creature entered the battlefield or not, for abilities that trigger whenever a creature enters the battlefield.
4/26/2014 If a God stops being a creature, it loses the type creature and all creature subtypes. It continues to be a legendary enchantment.
4/26/2014 The abilities of Gods function as long as they’re on the battlefield, regardless of whether they’re creatures.
4/26/2014 If a God is attacking or blocking and it stops being a creature, it will be removed from combat.
4/26/2014 If a God is dealt damage, then stops being a creature, then becomes a creature again later in the same turn, the damage will still be marked on it. This is also true for any effects that were affecting the God when it was originally a creature. (Note that in most cases, the damage marked on the God won’t matter because it has indestructible.)
4/26/2014 Your devotion to two colors is equal to the number of mana symbols that are the first color, the second color, or both colors among the mana costs of permanents you control. Specifically, a hybrid mana symbol counts only once toward your devotion to its two colors. For example, if the only nonland permanents you control are Pharika, God of Affliction and Golgari Guildmage (whose mana cost is ), your devotion to black and green is four.
4/26/2014 Numeric mana symbols (, , and so on) in mana costs of permanents you control don’t count toward your devotion to any color.
4/26/2014 Mana symbols in the text boxes of permanents you control don’t count toward your devotion to any color.
4/26/2014 Hybrid mana symbols, monocolored hybrid mana symbols, and Phyrexian mana symbols do count toward your devotion to their color(s).