Deus magnus est.

Latin usually does not use articles. There is no normal Latin word that directly matches English the or a/an.

So Deus can mean:

• God
• the god
• a god

Which one is meant depends on context. In many Christian texts, Deus with a capital D is understood as God, but grammatically the noun itself does not contain the article.

No. Latin adjective position is more flexible than English word order.

Both of these are possible:

• Deus magnus est
• Magnus Deus est

In many straightforward sentences, an adjective often comes after the noun, but it can also come before it for style, emphasis, or rhythm. So magnus after Deus is normal, but not the only possibility.

Latin often places the verb near the end of the sentence, especially in simple statements. That is a very common Latin pattern.

So:

• Deus magnus est = standard and natural
• literally, God great is

But Latin word order is flexible, and you may also see:

• Deus est magnus
• Magnus est Deus

The endings on the words do much of the grammatical work, so Latin does not depend on word order as heavily as English does.

Est is the third person singular present active indicative of esse, meaning to be.

So:

• sum = I am
• es = you are
• est = he/she/it is

Here it matches Deus, which is singular, so est means is.

In Latin, adjectives agree with the nouns they describe in:

• gender
• number
• case

Deus is:

• masculine
• singular
• nominative

So the adjective describing it must also be:

• masculine
• singular
• nominative

That is why the form is magnus.

Compare:

• deus magnus = a great god / God is great
• dea magna = a great goddess
• templum magnum = a great temple

It is nominative singular.

In this sentence, Deus is the subject, and the subject of a Latin sentence is normally in the nominative case.

Also, with esse (to be), the adjective that describes the subject is also nominative. So:

• Deus = nominative singular
• magnus = nominative singular

This is why the sentence is grammatically balanced.

It is an adjective, but more specifically it is a predicate adjective.

That means it is linked to the subject by a form of to be:

• Deus magnus est = God is great

Compare:

• magnus deus = a great god
  Here magnus is directly inside the noun phrase.
• deus magnus est = the god is great / God is great
  Here magnus is being predicated of the subject through est.

Sometimes Latin can omit a form of to be, especially in poetry, short sayings, or very compressed style. But in a basic prose sentence like this, est is normally expressed.

So for a learner, it is best to treat Deus magnus est as the full standard sentence.

Classical Latin manuscripts did not use capitalization the way modern printed texts do. In modern editions, capitalization often follows modern editorial practice.

So:

• deus is the normal dictionary form
• Deus is often capitalized in Christian or modern contexts when it refers specifically to God

This is usually a matter of writing convention and meaning in context, not a different grammatical form.

A common Classical Latin pronunciation would be approximately:

DAY-oos MAG-noos est

More carefully:

• Deus = DEH-oos or DAY-oos depending on how narrowly you pronounce the diphthong eu
• magnus = MAHG-noos
• est = est

In Ecclesiastical Latin, many people pronounce it more like:

• DEH-oos MAHN-yoos est or MAHG-noos, depending on local tradition

For a beginner, the most important thing is to recognize the word parts clearly:

• De-us
• mag-nus
• est

By itself, the most natural understanding is God is great or The god is great, because magnus is functioning as a predicate adjective with est.

If Latin wanted to say the great god as a noun phrase, that would more naturally be:

• deus magnus

And then if you added est, the sentence would still usually be understood as the god is great, not simply the great god exists.

Context decides a lot in Latin, but in a simple beginner sentence, the intended structure is:

• subject: Deus
• predicate adjective: magnus
• verb: est