Ought to is a unit. In older English texts, or modern texts whose authors are trying to sound old, one occasionally comes across ought separated from its to (?_Ought I to awaken him?_) but nobody would ever speak English that way except on a stage. In Modern English, oughtta is sufficiently fused to have developed its own "eye spelling", like wanna, gotta, shoulda, wouldna, and hafta.

Understanding the Context

Ought is ... While the usage of ought to has been declining steadily in the last 300 years, it is still incredibly common. (The linked Ngram shows that it is roughly 1/3 as frequent as the word table today, and table is not at all an obscure word.) The question is when should you use it, and when to use should or must. Why should I use "ought to"?

Key Insights

- English Language & Usage Stack Exchange 'Ought' is an archaic spelling of 'aught', which is another old word meaning 'anything' or 'any'. So the meaning is: None of the believers considered that any of the things they owned were theirs. This is born out by more modern translations of the passage. E.g. All the believers were one in heart and mind.

Final Thoughts

No one claimed that any of their possessions was their own, but they shared everything ... The current use of ought in standard English is a modal auxiliary (as present or future tense, mainly with to and infinitive). Etymonline says ought has been detached from owe since 17c. and provides the etymology of ought as below: Old English ahte "owned, possessed," past tense of agan "to own, possess; owe" (see owe).