Failgold isn't a substitute for a good economy, but most players around here can produce a good economy. So the big economic difference between the rest of us and a deity economy is primarily running failgold...particularly the multiple city national wonder failgold that is almost universally found in deity write-ups.
Choosing the wrong time or target for an attack will knock you out in pretty much any game if you have an appropriate stack for the level of difficulty, so again most players hereabouts will likely be able to pick a good target at a good time. The key difference I see in deity write-ups is the precision timing of the whip for optimal overflow and sustained production...so the attack on the right opponent at the right time can be done with a big enough stack to deal with that level of AI opponent.
I read through deity write ups and that's the big things I see that are different. If I wanted to play a deity game those are the things I would study up on.
You're intelligent, you should be able to to grasp the few things that are important for whipping in 2 sentences, which are, bigger whips are better, and whips just before growth minimize the time that the city needs to regrow.
And I never used Failgold of national Wonders in any of my HoF #1 rounds.
Now you should be able to win Deity :> .
(You're not

) .
Really, out of niceness: 90% of the players on this site are not able to plan an attack in that quality, that they'd succeed on Deity, and conquering 1-2 AIs is still easy, but building up an Economy that can hold such conquest on Deity, that's what 99% of the players here can not or have difficulties with. As my friend
Zx Zero Zx once said "normaly I trolololol the AIs by just whipping troops and watch them suicide themselves against my hills-cities, it's just that on Deity they still come with so many that it's still not possible"

.
Remember, you can try yourself, I already gave you the 2 keys that you wanted

. You'll be surprised that you'll simply lose 100/100 games, I did too, and I played Incans. As
TMIT once said, "Deity is just a completely different ballgame, it cannot be compared to Immortal or anything else" .
To imagine the bonuses / discounts AI gets on Deity, you must imagine that AI gets something like 4* bonus from era and -50% discount on most things, they simply build Infantries in 1T, and to trade you must pay 1.5 times the Beakers they have, Deity-AIs simply out-research you even with tripple Gold, without it it's like "woot, I made it somehow again, AIs have only 5 techs more than I have, I'm in a good position" or it's like "omg, I have 4 cities and they have only 10, I'm winning"

.