The Akatsuki is a group of villainous ninja who abandon their home nations and join forces to fulfill destructive goals. While they are united in their objective to capture and use the tailed beasts as weapons of war, most members have unique reasons for engaging in warfare.
Redditor /u/awesomehunder started to break down the different motivations behind each member of the Akatsuki, and their theory is deep enough to warrant further exploration.
Itachi Uchiha uses war as a way to protect his home, while Hidan wants to spread his violent religion. Deidara was coerced into joining the Akatsuki and now wants to blow things up for purely aesthetic reasons. Pain tries to bring lasting peace by showing the consequences of war - and he takes a stab at revenge while he's at it.
The Naruto manga also addresses the Akatsuki members' motivations, where Pain describes the seemingly endless incentives humans have for waging war. Like other Naruto fan theories, this Redditor's take is pretty intense and will have you re-examining some of your favorite Naruto characters.
Deidara participates in the Akatsuki and war for a simple reason: Violence is his inherent desire. He loves creating explosions because he considers them an art form. He doesn't care who he hurts in the process, as long as he's able to express himself. He acts on impulse, unconcerned with collateral damage.
Originally, Deidara didn't want to join the Akatsuki; he only did after Itachi challenged him. If he could defeat Itachi, the Akatsuki would leave him alone, and he could continue pursuing his goals in peace. But Deidara didn't stand a chance against Itachi, so he ended up joining. While he may now act on impulse, he was forcibly recruited into violence.
Orochimaru may not be a member of the Akatsuki during the Naruto timeline, but he was once part of the violent pack. He ultimately defects after realizing his aspirations don't line up with theirs.
He wants to achieve immortality by acquiring a powerful body for his consciousness. He leaves the Akatsuki after a failed attempt to take over Itachi's body and instead starts kidnapping orphaned children to run wildly unethical experiments on them.
Orochimaru represents war for the pursuit of personal gain and scientific discovery. Some Naruto fans have even compared him to Shiro Ishii and Josef Mengele, two real-world scientists who committed unspeakable acts of human experimentation during the Second Sino-Japanese War and World War II.
Pain and Konan's ultimate endgame - which they hope to achieve through leveling an entire city - is peace. They come from Amegakure, a tiny settlement that often gets caught up in the conflicts of larger ninja villages. Konoha's involvement in the warfare that made their childhoods a living nightmare makes the city a target for Pain and Konan's wrath.
In order to teach the larger cities what it's like to suffer endless invasions, and hopefully persuade them to rethink their vicious ways, the two launch an attack on the city, killing many innocents as well as those involved in the battles that ravaged Amegakure.
Thanks to a lifetime of painful war-related experiences, Madara believes humans are irredeemable, and the only way to achieve lasting peace is to hypnotize humanity into total docility using the Infinite Tsukuyomi.
This is similar to Konan and Yahiko's peace-oriented goals, but Obito and Madara don't believe war will bring concord. Instead, they think harmony can only be achieved through the total elimination of humanity, or through forcing them to only see and experience what Obito and Madara want.
Their motivations gesture toward a far more cynical view of human nature. This is especially true for Madara, who goes to great lengths to make Obito's life as miserable as possible in order to manipulate him into joining his side.