Perhaps a new, powerful and mysterious ninja who has a vendetta against the Fourth Hokage (Naruto's father). Since he can't directly take revenge on the Fourth Hokage, he decides to target Naruto. He uses his influence and devious plans to turn Team 7 against Naruto by making them believe Naruto is involved in some dark conspiracy.
Danzo could also be the main antagonist. He is known for his underhanded methods and distrust of anyone with too much power. Since Naruto has the power of the Nine - Tails, Danzo might spread lies within Team 7 to make them think Naruto is a danger, causing them to betray him.
It could be the very villagers who once looked up to Naruto. Their betrayal could turn them into antagonists as they might try to further harm Naruto to protect their own interests.
Perhaps the main antagonist is actually an old enemy who manipulates Naruto's team into abandoning him. This enemy could be using mind - control or false information to drive a wedge between Naruto and his team. They do this to weaken Naruto, knowing that his strength comes from his relationships.
There could be a group of bandits who have been causing trouble around the areas where Naruto is training Team 8. They don't like the idea of a strong team emerging in their territory. So, they start attacking the team during their training sessions. These bandits might have some crude but effective combat techniques and they also use the terrain to their advantage, which makes them a formidable antagonist for Team 8 during their training with Naruto.
The main antagonist might be an organization that wants to take over the Hidden Leaf Village. They see Naruto as a major obstacle because of his strength and influence among the villagers. So, they devise a plan to make everyone in the village betray Naruto. They use mind - control techniques or spread misinformation on a large scale to achieve their goal. This way, they can weaken the village from within before making their move to take it over.
It could be a former member of Akatsuki who has a personal vendetta against Naruto. Maybe they escaped from prison and now they want to take revenge on Naruto for all the things he did to Akatsuki. They would be a very powerful and dangerous antagonist as they possess knowledge of many dark jutsus.
The villagers themselves could be the antagonists in a sense. They have always been somewhat afraid and resentful of Naruto because of the Nine - Tails. Their constant negative attitude towards Naruto could influence the decision to kick him out of Team 7. They might pressure the village elders and Kakashi into believing that Naruto is not a suitable member for the team and that he poses a threat to the safety of the other team members.
Maybe the main antagonist is an evil organization that has been secretly infiltrating the village. They target Sakura because of her skills and knowledge. They deceive her into believing that her village is the real enemy, causing her to betray her comrades.
It could be a rogue ninja from a rival village. This ninja has a personal vendetta against Konoha and specifically targets Team 10 because of Naruto's presence. He might be jealous of Naruto's growing power and fame and wants to prove himself by defeating the team.
It might be a rogue ninja from the Wave. They could have a vendetta against Konoha and see Naruto as an easy target to frame and cause chaos between the two places.
Obviously, Kami would be the main antagonist. Since the title says 'naruto betrayed by kami', Kami is the one doing the betraying, which makes him the bad guy in this fanfiction.