The Muslims believe only in --> Muslims believe in

Only is essential for the semantic context.

The English is saying that Muslims don't believe in anything except "Allah is the only god and Mohammad is the last prophet." The essential semantic restrictions are already provided by "only God" and "last prophet," each of which indicates uniqueness.

Not necessarily. Provided god is unique and his prophet is last, they could still believe in aliens, zombies and the superiority of green cheese.

That's my point: your English says different.

+1

The essential contrast is given schematically by the contrasting sentences:

(1) They believe in that.

and

(2) They believe only in that.

These are semantically equivalent to:

(1) They believe in that, and they may or may not believe in anything else.

(2) They believe in that and nothing else.

The word "only" functions in exactly the same way in the pair

(3) I want fish.
(4) I want only fish.

It is a sad and confusing truth that careless American speakers may say, "I only want fish" when they mean (4). Do you have something like this in mind?

I'm not American...
Thanks for the explanation.
My translation is based on two facts,
1. The original EO phrase
2. Knowledge and understanding of the context.
If you inspect the EO original, the word "only"="nur" occurs. It would have been careless of me to omit it.
If I had omitted the "only", I would have certainly changed the meaning of the original text, implying that Muslims may indeed believe in unicorns and dragons. However, according to Islam, they may not.

Your explanation is clear and correct.

It is true that "only" here eliminates the possibility of belief in unicorns and dragons. It also eliminates the possibility of belief in anything else--except what can be deduced from the two beliefs named. This is throwing the baby out with the bath.

However, as your sentence is both structurally sound and natural, and as it seems to be an accurate translation, I must concede that you have done well, even as I condemn the Esperanto original. (For meaning. It too, as far as I can tell, is structurally sound.)

Thank you for responding to what has turned out to be an inappropriate complaint.

This means Muslims don't believe the Earth is round...

Or icosahedral.

A belief is something for which there is no inherent proof. The fact that the earth is approximately round is thus not a suitable subject for this discussion. If, however, the proof of the existence of an additional god were to become scientifically viable, the theology of Islam (one of the five pillars of faith) would instantly collapse. A fine example is, if Christians could provide a proof for the deity of Jesus or for the trinity. Another example is, if anyone would demonstrate a verifiable and reproducible prophetic ability, thereby dethroning Mohammad as the last.

This sentence states : Muslims believe only (proposition A), where proposition A = Allah as the unique God, and Mohammad is the last prophet

That means that Muslims don't believe anything but proposition A, so that means they don't believe in Unicorns.

What CK is proposing is different :
It states that Muslims believe in (proposition B) and (proposition C)
where proposition B = Allah is the only God
and proposition C = Mohammad was the last prophet.

In this case, Muslims may believe in Unicorns.

So the 2 sentences are not the same at all from a logical point of view.

Quite right, but I should put it this way: It appears that CK has either not read or not understood the chain of comments preceding his.

Sorry, if what was?

There are 3 issues at hand.
1. The correct translation - since the English phrase is not the original text, the question remains whether the translation correctly conveys the meaning of the original.
2. The logical issue = the mathematical proof that
(A and B) != ((A and B) and !C)
3. The theological issue, whether or not Islam or Sharia allows a belief D, such that (D!=A) and (D!=B) and (D!=X where X is derived from either A or B).

Each of the issues merits a different discussion, but we in Tatoeba must adhere to issue 1.