Really? No Crowning Moments of Awesome for a game where you can become a demon overlord or The Messiah and challenge God to a duel, after punching out around 5 assorted Cthulhus?
What about controlling the demons through technology for the progress of humanity? It causes a singularity on par with the Industrial revolution. Even Metatron acknowledges that Humans Are Special
One definite example is a possible result of you taking up Kaido's challenge mid-way through. It's Honda and Kaido against your squad to see who can kill more demons. Kaido gleefully notes he loves a handicap when Yuzu points out it's 4 vs 2, making the odds two to one in your favor. However, you can instead send out just the main character, reversing those odds and royally pissing off Kaido. And still win.
The 8th Day scenarios from Overclocked have their share, but the crowning one is undeniably in Naoya's route. The lockdown's still in effect. Yuzu and Midori are still avoiding you. The Shomonkai are FURIOUS that you've killed Belberith. The government and SDF are too scared to fight back against the orders of the Angels. The Angels have taken center stage and are basically forcing the demon tamers trapped in the lockdown to hunt you down under pain of death, and it doesn't take a genius to figure out they'll kill said demon tamers anyway once they've outlived their usefulness. If the tamers FAIL to kill you, Metatron is going to vaporize the planet with God's Thunder. And through all of this, you're sparing the people trying to kill you, trying desperately to convince them you want to protect them from the angels, all apparently in vain. Things aren't looking good. At all. It comes to a head when you're surrounded in the park by tamers, begging you to let them kill you. Cue Yuzu's entrance. She calls out the tamers and declares her support for the heroes. The Shomonkai, led by Amane, are next to stand behind you, followed by Izuna and the SDF. The demon tamers themselves even realize they've been fighting the wrong people and tell Metatron himself to shove it. When the big guy himself comes down with an armada of angels, EVERYONE stands against him. It's AMAZING seeing the demon tamers fighting alongside the SDF and Shomonkai, after they had been enemies throughout the entire game. Seeing all these factions standing together against the Angels brings to mind all of the cowed kids on the playground finally nutting up and standing up to the big bully. And it is 100% awesome.
There's more to that. After the protagonist manages to defeat Metatron in combat, he attempts to call down Michael, Uriel, Raphael, and Gabriel to kill everyone. The protagonist's response is to use the power as King of Bel to call forth several demons to attack him, inclding Belial and Beldr.
Yuzu and Midori get another one in the evil Naoya 8th Day that arguably tops their actions in the good version. Distraught at your wanton slaughter of the tamers fighting against you, Yuzu and Midori stand against you, lead a small group of Demon Tamers to take you on despite your incredible power, and their determination to do so is so strong that Metatron not only praises their bravery, but descends from Heaven to help them. It doesn't work out, but it says a lot about the the two that they were willing to face off against somebody they both thought as a friend, moreso in Yuzu's case, while knowing that they had no real chance of winning.
The Main Character pulls one off on the third day of the Tokyo Lockdown, by beating up an (almost) immortal demon that was going to kill hundreds of people. How does he do it? With a picture of mistletoe on a cellphone strap.
And that doesn't mean all of his special attacks and magic suddenly started working on the demon either; The Main Character goes toe-to-toe and beats the demons down with his fists. Whether he's wearing the strap on around his wrist or using his cell phone as a knuckle duster is totally up to whatever the player feels would be most awesome.
And then it comes full circle in most endings when you have to fight ALL the Bel-demons again. Cue Curb-Stomp Battle for any adequately leveled player. Against a few Eldritch Abominations raging for your blood and the right hand of Lucifer, no less.
While it's rather dark, the Chaos End qualifies, ending with the main character, now the Demon Lord with eyes in permanent rape-stare, casually with-calling the legions of hell in front of the SDF, then going off to have war with GOD. Kind of makes Metatron's e-mail to his now unneeded COMP rather silly looking.
Showing Lucifer you're worthy of the mantle of King of Bel counts. Defying the Devil himself, he who calls himself your father - even braving Megidoladyne, at least twice, and more than likely four times, until he no longer has anything else to use against you. One can feel him smiling just like he smiled at the Hito-Shura (as mentioned above) while he calmly stated Belberith had zero chances against you.
Beating Babel in most paths. But nothing beats Gin's path, where you command it to banish all demons from within the Yamanote Lockdown... and he does exactly that. Including your own. Which only makes it all the more awesome when you get to destroy that devil tower thing with your own fists and magic.
Defeating Okuninushi in Amane's eighth day. Okuninushi told the protagonist that he'd abdicate Japan if the protagonist redeemed Naoya. All efforts failed, and Okuninushi prepared for Japan's destruction and recreation, causing the heroes to engage him in battle. He can revive a limitless amount of times, and after the second, despair hits the party. However, Naoya shows up and prevents Okuninushi from reviving again while calling Okuninushi out for ignoring being killed by his brother twice while the protagonist stood up to it and forgave Naoya. After he is defeated, Okuninushi sees that Naoya has actually taken a single step towards redemption. While he knows that Naoya can snap back, he accepts that this slight change is enough for him and abdicates Japan to God. And of course, since this is an Atlus True Final Boss, you WILL feel satisfied.