Meet Theophilus.

Theophilus is the AI assistant built into Theodia, the offline Bible app. He lives in the AI tab, he's available whenever you want a study companion, and he never forgets that the Bible is the point.

Who is Theophilus?

A Bible study partner who can read with you, look things up for you, and do the small tasks that would otherwise break your reading flow. Ask him to find a verse, look up a Greek word, write a study note, compare two translations, pull every cross-reference for a passage, or summarize a chapter. He does those things against the same data Theodia uses, so the answer is grounded in the same translations and commentaries you see in the rest of the app.

He is deliberately conservative. He will not delete a note, remove a bookmark, or change a setting without you confirming. He won't guess at a verse reference if you gave him an ambiguous book name — he'll ask. And he cites the references he uses in the standard "Book Chapter:Verse" format, so any reference he mentions is clickable and opens the reader at that verse.

What Theophilus can do

Read with you

  • Look up any verse, in any installed translation. "What does Romans 8:28 say in the NET?" or "Show me John 3:16 in the BSB" — Theophilus reads the verse, quotes it back, and can open the reader at that exact location.
  • Read a whole chapter. "Read Psalm 23 in the KJV" returns the whole chapter; the format is clean and copy-paste-friendly.
  • Compare a verse across every translation. "Compare Philippians 2:6 across all versions" lays out the verse side-by-side in every Bible you have installed, the same view as the in-app Compare screen.
  • Summarize a chapter or a passage. Aimed at the user who wants a quick orientation before diving in.
  • Search the Bible by phrase or word. "Find every verse with 'agape' in the BSB" or "Search for 'valley of the shadow of death' in the Psalms." Theophilus uses the same full-text search index the in-app Search screen uses.

Study with you

  • Cross-references for any verse. "Show me the cross references for Hebrews 11:1" — the same cross-reference database the rest of the app surfaces, not a web lookup.
  • Lexicon lookups. "What's the Greek word for 'love' in 1 Corinthians 13?" returns the lemma, the Strong's number, the parsing (if applicable), and the definition. Theophilus has access to the same lexicons the in-app Lexicon screen shows (MCGED, SECE, TBESG, TBESH, TRLIT).
  • Commentaries on demand. "What does Matthew Henry say about this verse?" or "Pull Henry and AIC on Romans 9." Returns the same commentary text you'd see in the in-app commentary view.
  • Devotional reading. Theophilus can open a devotional entry for today's date, or for any specific date, from the bundled devotional library.
  • Hymn lyrics search. "Find the hymn 'Amazing Grace'." The bundled hymn book is searchable the same way.

Take notes and bookmarks for you

  • Create a bookmark from a conversation. "Bookmark that verse, please" or "Save John 3:16 to my Sermon Prep folder." Theophilus will confirm before writing, and the bookmark lands in the folder you specified.
  • Move, rename, or delete a bookmark. With confirmation.
  • Create, update, or delete a Bible note. Anchored to a specific verse.
  • Manage study notes. Create, edit, organize into notebooks, delete. The two-note system (verse-anchored Bible notes vs. freeform study notes in notebooks) is the same one the rest of the app uses.
  • Manage highlights. Create or clear highlights on a verse. Clearing all highlights is gated behind the same confirmation the in-app UI requires.

Answer questions about the Bible and theology

  • "What is the Protestant canon?" or "Who is the Theophilus that Luke's gospel is addressed to?" — questions like these are in-scope and Theophilus has a system prompt that frames him as a knowledgeable study assistant, not a generic chatbot.
  • Difficult passages. Ask about Romans 9, the imprecatory psalms, the vineyard workers in Matthew 20. Theophilus answers in the same voice the rest of the app uses — careful, citation-heavy, willing to say "different traditions read this differently" when they do.
  • References, always. Every verse or passage Theophilus mentions is rendered as a clickable link in the chat, so one tap takes you to the verse in the reader. The references survive into the conversation history.

How Theophilus works under the hood

This is the part of the page that earns trust with the more technical reader. You can skip it; it doesn't change how the assistant feels to use.

  • Tool-using, not just chat. Theophilus has structured access to ~50 tools in the app — read verse, open verse, search, cross-reference, lexicon, commentary, bookmark, note, and so on. When you ask a question, he picks the right tools and calls them against the same local data layer the rest of the app uses. He is not a chatbot that was fine-tuned to talk about the Bible; he is a Bible app with a chat interface.
  • Same data, every time. The Bible translations, the lexicons, the cross-references, the commentaries — all the data Theophilus reads from is the same data you see in the Bible, Search, Lexicon, and Cross-Reference screens. There is no second, web-based, possibly-stale copy he might be quoting from.
  • You choose the model. The app talks to any OpenAI-compatible endpoint. In Settings → AI Assistant, you set the URL, the model, and the API key. There is no Theodia-branded model you have to subscribe to. Popular options:
    • A hosted model (OpenAI, Anthropic via a proxy, etc).
    • A self-hosted llama.cpp or Ollama server on your home network.
    • A Bible-specialized model published by the Theodia project, downloadable directly in the app (see below).
  • Your API key stays in the secure enclave. The key you paste into Settings is stored in the iOS Keychain or Android Keystore via the platform's secure store, used to authenticate the requests you send, and never logged or mirrored anywhere.
  • Streaming responses. Theophilus streams his replies token by token, so you see the answer start forming as he thinks through it. There is a "Stop generating" control on every reply that aborts the request.
  • Multi-conversation history with projects. Organize chats into named projects ("Sermon on Romans 8," "Genesis study group," "Personal devotions"), rename them, archive them, and switch between them from the chat drawer.

Run Theophilus fully on-device

For users who never want their reading history to leave the phone, Theodia supports downloading a Bible-specialized language model that runs locally. The download is one tap in Settings → AI Assistant → Manage Models, the model lives in the app's private storage, and once it's installed Theophilus runs end-to-end without any network call. The on-device model is the right choice if:

  • You're studying in a context where you can't (or don't want to) reach an external service.
  • Privacy is the primary constraint and "fully on-device" is the only acceptable answer.
  • You're using a self-hosted model in a development context and want to test against the same model the app will use in production.

The model catalog is curated: the app shows you what's downloadable, the size of each model, and lets you remove a model from the device when you're done with it. Models are verified with a SHA-256 checksum after download, so a corrupted file is detected and the user is told to retry.

A small note on the name

Theophilus is a Greek name meaning "lover of God" or "friend of God." It's the same name the Gospel of Luke is addressed to in its opening line ("Inasmuch as many have undertaken to set down an account… it seemed good to me also, having followed all things closely for some time past, to write an orderly account for you, most excellent Theophilus"). The assistant is named after the recipient of the first Christian history — a friend of God who was about to be told the story. We thought that was the right name for a Bible study assistant.

Privacy and your data

Theophilus follows the same privacy rules as the rest of Theodia. The full disclosure is in the privacy policy; the short version for the AI tab:

  • Your conversations are stored on your device. The chat history lives in a local SQLite database. It is not synced to a server, and there is no account that would let anyone else see it.
  • Your API key never leaves your device except inside the request to the endpoint you configured. We do not run a server that proxies your AI traffic.
  • The app does not log your prompts or replies. The in-app log viewer shows your own actions and framework errors; AI content is not logged.
  • Deleting a conversation deletes it from the device. The delete control in the chat drawer is final.
  • On-device mode means on-device. When you have a local model installed and the AI endpoint URL is empty, Theophilus makes zero network calls.