The Lord lets the Nazis know just what He thinks of the National Socialist agenda. And THAT, folks, is why you don't take the Ark of the Covenant lightly.
And not just frying the Nazi soldiers and melting the leaders' faces when they open the Ark, either. Earlier there's the scene with the Ark in a box with the Nazi swastika on it. The Nazi emblem (not to be confused with the original Hindu-Buddhist swastika) gets burned off from inside the box. God's personalized Mene Mene Tekel Upharsin to the Third Reich.
We must elaborate, Indy is literally thrown under a bus! No seriously. And they STILL can't stop him!!! Indiana Jones is a Colonel Badass, just not a Colonel.
He did become one during WWII for the OSS.
The awesome fist fight with a guy twice his sized in front of a rotating plane.
The bar fight in Nepal. Rather than dramatic orchestral scores, it's a lot of rough and bloody fighting loaded with flames covering every surface of the building, props getting smashed, and a Giant Mook responding to having his arm set on fire by trying to punch him with it.
The villains are getting away in a submarine! What now? Swim to the sub and climb aboard, obviously. Blatant use of the Rule of Cool, of course, because the hatch was already closed (so Indy can't get inside without being noticed), there's no room to hide inside a U-boat anyway, and he obviously can't just cling to the hull all the way through the Mediterranean. Still really, really awesome.
A deleted scene showed him holding on to the periscope.
Make it even better when the ship captain asked to locate Indy after the Nazi reclaim the Ark and Marion. He does, spotting Indy stowing away on the sub. The whole crew of the ship cheer him on.
Question: What do you do when you try to steal a Nazi uniform but it's the wrong size? Answer: You knock out the Nazi guard berating you for being drunk with one punch and take his uniform.
Marion drinking Belloq under the table. Sure, Toht showing up renders it moot, but it's still awesome.
One for Sallah for noticing the dates were poisoned and managing to catch it mid-air just as Indy was about to catch it in his mouth.