quantifiers

Came across a sign-age stating: "God is one".
The proposer being one of the many god men.
However what is dropped is the quantifier "All".
'All' considered to be an indefinite pronoun generally when the sum quantity of the subject under consideration is unknown.

'All' can take singular as well as plural depending on the subject.

For starters the statement implies a multiplicity of gods, which makes us wonder the state of mind of the proponent.

'God' is in the singular, the plural but obviously would be 'gods'.
So why state the obvious.
example: An apple is one apple. Stating the obvious.

For the simplest reason of all, if I get your belief then I get you and if I get you then I get what you have.

Which is the oldest rule in the book of con.
Get the people to believe in you, You can get them to believe in you, if you believe what they believe.
In other words these are days and times of convenience, if it is convenient to state God is one, say so, which implies that there are many Gods, but then he/they is/are one. Clearly something is amiss somewhere.

Which gets us to what grammar has to say about indefinite pronouns:
"On the surface, indefinite pronouns seem simple and harmless, but they often cause confusion for writers."

Similarly, the propose is making a harmless statement so to say, but then he is creating confusion too.

Which is so very apt to convenient times as ours.
Hopefully, once we know what they are pulling over our eyes we'll usually make the correct choice.
That is, 'hopefully'.