Well SMT 2 was just an angry game from what I hear. I recall hearing that the guy behind the series said something to the effect of "the gods in this aren't used in a religious sense... Yahweh just represents a generic overlord" or something to that extent so it's really not like the SMT series is an attack on religion.
They often say things like this as a disclaimer, and it works since the Christian population in Japan is so small and not the same as the Christian conservative base in the US (i.e. flies off the handle at every perceived slight), but the way it discusses the nature of the Christian God and how He is worshipped is definitely a criticism of Christianity, not just of the religion itself but of its adherents as well. A traditional Japanese view of Christianity is religious intolerance and forced conversion, seen through the many attempts at Christian religious imperialism throughout Asia and much of the world. It's a stark contrast to the spread of Buddhism, which was spread peacefully and willingly with great religious tolerance. A "generic overlord" doesn't make much sense since there is no similar concept in Shinto or Buddhism. Buddhism has no such figure, and the central figure in Shinto is Amaterasu, the Sun Goddess, which has little in common with Yahweh.
I am aware that it's pretty dark but didn't know that the devil was portrayed as a good guy and Yahweh (directly referencing the name of God) as the bad guy. It sounds pretty satanic from the surface if the goal of the game is to join force with the devil and attack God.
Lucifer is not portrayed as a "good guy." He just represents one of the possible paths you can choose, the very extreme of free will. Yahweh is only referenced in earlier games directly, in Nocturne it's more roundabout, but the fact that many angels are in the game directly doesn't leave much room for doubt as to who their boss is.
The game is about free will. It's not about "joining forces with the devil to attack God." It's about choosing what to do. You can also choose the path of law and order, which is considered in the game to be the path of God. It's not satanic. It just allows you to explore different possibilities. Who you perceive to be "the good guy" is reflective of what you value. If you value order and protection of the weak, you will choose that path. If you believe everyone has the right to choose how to live their life, despite the fact the weak will suffer or perish, you choose a different path. SMT3 is unique in that it also has other paths open besides these main two.
I can handle dark games but not satanic games due to my belief. If Chacrana as a Christian didn't find Nocturne offensive, I guess I'll try it someday
I'm Catholic and was a theology minor from university and I didn't find it offensive at all. Even if someone Christian did find it offensive, you should experience it for yourself before you reject it. Don't be like all those Christians that boycotted movies like The Last Temptation of Christ without having seen it or without even knowing what the actual story is about.
The main reason I've been reluctant to pick it back is that I've heard it's quite hard. I heard that it was even more challenging than the DDS games.
It's VERY hard. It's really a merciless game, and many regular enemies have the potential to wipe you out if you're careless. It's one of the few games that makes me want to throw my controller across the room.