[name_f]My[/name_f] fiancé and I were bantering around middle names for [name_m]Nilo[/name_m] (prn nee-loh) the other day, and we came up with the fantastic [name_m]Nilo[/name_m] [name_m]Poseidon[/name_m].
Pros: it’s SO COOL
Cons: We’re in a small Catholic community so naming our son after a god from another pantheon would be quite problematic
But it’s SO COOL!
Talk me out of it 
You could have a name that has a similar sound to [name_m]Poseidon[/name_m]? Such as [name_m]Nilo[/name_m] [name_m]Dion[/name_m] (although as I wrote that I realised [name_m]Dion[/name_m] also has mythological links to another pantheon- it is a less obvious one though).
Alternatively you could give him two middle names, and have [name_m]Poseidon[/name_m] be the last one that is tucked away and les people know about- the other middle name can be used in settings where [name_m]Poseidon[/name_m] could be problematic. E.g. [name_m]Nilo[/name_m] [name_m]Henry[/name_m] [name_m]Poseidon[/name_m]
No talking you out of it here, I LOVE it!
If you both love it, got for it. Other people’s opinions don’t matter & let’s be fair unless you’re going to only ever address him in public with both names people will soon forget about the MN when the next ‘shocking’ thing comes along 
To be honest, as a Greek person I’d find it odd if I came across it. We don’t use Poseidon as a name here in Greece, because the names of the “big three” (Zeus, Poseidon & Hades) are considered off-limits. It definitely sounds cool but it’d just be a strange choice considering its cultural context. It’s a name with a strong history and cultural significance, and especially unless you’re very passionate about and educated in Greek myth & ancient Greek culture I wouldn’t use it just because it sounds cool.
For a similar sound, maybe Nilo Gideon, Nilo Auberon, Nilo Harrison, Nilo Remington, Nilo Solomon or Nilo Tennyson? Or if it’s the cool / out-there feel of Poseidon that you like more than the sound, maybe something like Nilo Archer, Nilo Endymion, Nilo Everest, Nilo Hyacinth, Nilo Hawthorn, Nilo Jupiter, Nilo Meridian, Nilo Peregrine, Nilo Somerled, Nilo Wilder, or Nilo Zephyr.
[name_m]Nilo[/name_m] [name_m]Dion[/name_m] sounds lovely! Thanks for the suggestion
Thanks for the support! It is such a cool combo. I’m not a huge fan of double middles but [name_m]Nilo[/name_m] [name_m]Henry[/name_m] [name_m]Poseidon[/name_m] also sounds cool!
That’s a great point about “the big three” I hadn’t considered. This is why I love getting perspectives from all cultures on here!
Both my fiancé and I really love your suggestion of [name_m]Nilo[/name_m] [name_m]Gideon[/name_m]! It made us stop and smile It’ll definitely be in the options!