Entriamo in chiesa insieme.

Entriamo is the first-person plural form of entrare in the present tense, so it literally means we enter / we are entering / we go in.

It can also function as a first-person plural imperative:

• Entriamo! = Let's go in!

So in this sentence, context decides whether it is:

• a statement: We go into church together
• or a suggestion/invitation: Let's go into church together

Italian often drops subject pronouns because the verb ending already shows who is doing the action.

So:

• Entriamo already means we enter / we go in

You could say Noi entriamo, but that adds emphasis, contrast, or clarity:

• Noi entriamo, loro restano fuori. = We go in, they stay outside.

In a neutral sentence, leaving out noi is completely normal.

With entrare, Italian normally uses in to show movement into a place:

• entrare in casa
• entrare in ufficio
• entrare in chiesa

Alla chiesa would mean something more like to the church, not into the church. It does not fit naturally with entrare here.

So:

• Entriamo in chiesa = We go into church
• not We enter to the church

Italian often leaves out the article in some common place expressions, especially when the place is seen in its usual function rather than as one specific building.

So:

• in chiesa = in/into church
• a scuola = at/to school
• in banca = at/to the bank

Here, in chiesa sounds natural and idiomatic.

If you want to stress a specific church building, you are more likely to say:

• nella chiesa
• in una chiesa
• in quella chiesa

In this sentence, it means into church because the verb entriamo already shows movement.

Italian in can sometimes correspond to either in or into in English. The verb helps you understand which one is meant.

Compare:

• Siamo in chiesa. = We are in church.
• Entriamo in chiesa. = We go into church.

Yes, you could, but it changes the nuance.

• Entriamo in chiesa insieme sounds more general and idiomatic.
• Entriamo nella chiesa insieme points more clearly to a particular church building.

So if you are talking about a specific church that has already been identified, nella chiesa can be a good choice.

Insieme is flexible.

The original sentence:

• Entriamo in chiesa insieme

is natural and neutral.

You can also say:

• Entriamo insieme in chiesa — also natural; slightly different rhythm
• Insieme entriamo in chiesa — more emphasis on together

So the position can change depending on emphasis, but the original order is very common.

It can be either.

Because entriamo can be both present tense and first-person plural imperative, the sentence may mean:

• We are going into church together
  or
• Let's go into church together

Usually, context and tone of voice make it clear.

Literally, chiesa means church. In this sentence, because of entriamo, it most naturally refers to the place/building.

But the expression in chiesa can sometimes carry the broader sense of being at church in the religious or social sense, not just inside a physical structure.

So here the most direct reading is:

• entering the church building

while still sounding like a normal everyday phrase connected with going to church.

Entrare focuses on the action of going in / entering. It suggests crossing the threshold.

Compare:

• Andiamo in chiesa. = We are going to church.
• Entriamo in chiesa. = We are going into church / entering the church.

So entrare is more specific than andare. It highlights the moment of going inside.