Cross simply indicates Religion
Even Enel's Throne had a Cross
It's like Oda is using it as Universal Symbol for Most Religions
Doesn't mean that all People who hold a Cross have same Beliefs, it simply indicates that They Worship Someone
For Example, Graves are marked with Crosses in many Places (East Blue, Fishmen Island, Arabasta, Thriller Bark, Germa ... etc)
We are supposed to believe that Most OPVerse's Population believe in Higher Power
But so far, Only Three Characters seem to include the Cross as Part of their Design, indicating They actually have an Idea of who this Higher Power is
With Kuma it's revealed He worships Sun God
But Remaining Two are Mihawk & Moria, and i believe They Worship another God who is Final Villain
When We finally see Nika's Flashback, just like He ended up being called Sun God, there will obviously be a Villain in his Flashback who also was called God (Basically Enel of Story), and as Gan Fall Explained, He believes God is just a Title for someone who Rules, someone who cares for his People (And when Enel was gonna Destroy Skypiea, Conis was seen Praying, and then Luffy was shown saving everyone, the Scene played out as if it was Luffy who answered her Prayers)
So Sun God represents the Guy who saved the Day, hence why They call him God
But there is a Villain who was called God because He was Invincible & forced everyone to treat him that way
This Villain, this Self-Proclaimed God of OPVerse is who Mihawk & Moria Worship (Especially Mihawk)
And this is Pretty Clear, Zoro is Pirate Hunter, Mihawk is Marine Hunter, Zoro is Samurai-Like, Mihawk is Knight-Like, Zoro Grew Up as an Underdog, Mihawk probably Grew Up as a Prodigy, Mihawk is Clairvoyant-Like, Zoro is Worst at Directions, Zoro is Atheist, Mihawk is obviously Very Religious
Why is He not in his Church or Worshipping Place or near his God? Cuz just like Zoro couldn't go back to his Home cuz He got Lost, Mihawk also can't go back to his Home but this time it's because his Island that is Lost (Opposite of Zoro just like everything else).
So Mihawk comes from an Island that is "Lost", it's possible that Mihawk Originates from Ancient Kingdom
And Zoro always Fights Villain's Henchman (But who isn't 2nd in Hierarchy)
So when Final Villain shows up, Mihawk is gonna be his Obedient Henchman (Someone who Hypes his Boss)
Mihawk is Henchman of Strongest Villain Ever (Literally Enel of One Piece)
So Cross Guild is gonna become Organization under Final Villain's Rule, with Buggy as his No. 2 (Literally why there is Cross in it's Name)
Mihawk's Entire Design simply Indicates Existence of a Character who even WSS considers to be God
And He isn't a Celestial Dragon nor Sun God nor Anyone We've seen so far, otherwise Mihawk would be kneeling for Imu or Liberating Slaves
Mihawk's God is Powerful Enough to make WG, Elbaf & Yonko look like a Joke
Only Luffy can Beat Him because for some Reason He Counters him, just like Enel's Case
As for World Government, They simply represent Satanic Cult with Imu being their High Priest, and their entire Goal is to Summon their Ruler Satan (Imu is leading this whole Operation), They are basically like Illuminati who are believed to Run World Affaires both Secretly & Publicly, and they are Preparing the World for Arrival of Anti-Christ, so that They start a War against Self-Proclaimed God of OPVerse
And this was shown in Fishmen Island Arc, there is One Character who Challenged God of OPVerse & was Cursed (Just like Satan) & WG is trying to Summon him after preparing a better Army this time, and this Guy would wear Straw Hat shown in Mary Geoise & He would attack Fishmen Island because He seeks Shirahoshi (Poseidon), and his Origin Story is same as Davy Jones who is considered Most Evil Pirate Ever, They literally called him The Devil
It's none other than Vander Decken
OP Story is about World Government Worshipping Satan (Vander Decken whose Powers were Inherited by Man With Burn Scar)
And Freedom Fighters Worshipping Sun God (Nika whose Powers were Inherited by Luffy)
And Majority of Others Worshipping Sea God (Final Villain whose Powers were Inherited by God of Elbaf)
As Dorry/Brogy said, when Two Fight, it's God of Elbaf who decides who is Right & grants Divine Protection to Winner
Divine Protection from New World to Little Garden? He obviously have Enel-Like Presence
One Piece Story is simply about Atheist vs God vs Devil
Why do you think Oda made his Japanese-Like SH (Zoro) say "I don't Pray to God"?
It's cuz the Story is about Oda's Atheism beating both Religious People & Devil Worshippers
With All Three having different idea of what the Word "God" means
