"proper concept" is correct and usable in written English.
You can use it to refer to a concept that is deemed as acceptable or correct in a particular context. For example, "It is important to understand the proper concept of cause and effect in order to understand the physics law of motion."
I don't think a Jewish or Christian or Islamic state is a proper concept.
In another sense, though, we can have a proper concept of God, that is, one that applies only to God.
Due to the singularity of the possible solutions, we introduce a new and proper concept of periodic boundary value conditions.
The will's ability for self-determination according to universally binding laws conveys the objectivity demanded by the proper concept of reason.
Now in one sense we can't have a proper concept of God in this life, since we can't know his essence as a particular thing.
For a perfect knowledge of something it is sufficient that our intellect is able to single out the object in question against others by means of a proper concept.
In this paper evolutive laws and constitutive relations in non-smooth plasticity and viscoplasticity are presented by means of a formulation which takes advantage of the proper concepts required to deal with non-smooth problems in plasticity and viscoplasticity.
This is one of the main reasons mathematicians have introduced some suitable time scales such as periodic time scales and almost periodic time scales, and so on, before even they give the proper concepts of functions defined on time scales.
Not only can we come up with concepts that apply univocally to God and creatures, we can even come up with a proper (distinctive) concept of God.
Even within biology proper, this concept operates at many different levels.
Independently of the cleaning device the tube cooling channels and its proper support concept has to be developed.
