It's odd. My experience of talking to American Christians about Indiana Jones is that they love the films, except for Temple of Doom, which they hate. Temple of Doom was my favourite of the first three, and is still my favourite. Possibly because the peril isn't just Germans with guns.
But in a more profound way, this film is also the odd one out of the four. And yes, Indiana Jones was probably due for an expedition with one of the ancient American civilisations, but there are definitely strong X-files-type sci-fi elements as well. It even starts with the Russians invading Area 51 to try to find something from the UFO crash at Roswell...
The Russians protested about this film. But that's just New Cold War scaremongering. Actually it makes sense if when Indiana Jones was 40 he was up against the Germans to be up against the Russians when he's 60. And they don't come off anywhere near as badly as the Germans (let alone the Thuggi) do in the other three films. Their position makes perfect sense - they want knowledge, especially knowledge that might help militarily. They aren't trying to use weird occult powers or anything.
From an action point of view, it's probably the best of the 4 Indiana Jones films, and the compulsory gross-out animal scenes are great too. From a plot point of view, it's possibly the weakest. But it's still great fun.