Our country is spiritual country, theirs . . . . . . religious.

In this sentence, the subject "country" is singular, so the verb should also be singular. Therefore, the correct form is "Our country is spiritual, theirs is religious." Option A correctly provides the singular form of the verb "is" to maintain subject-verb agreement.

The sentence structure involves a parallel construction, comparing two aspects of different countries. The first part of the sentence establishes that "Our country" is a spiritual country. To maintain parallelism in the comparison, the second part should also convey a similar idea about "theirs."

Here, "spiritual country" and "religious" are conceptually parallel. The appropriate verb to use in the second part of the sentence is "is" to maintain subject-verb agreement. The subject "country" is singular, requiring the singular form of the verb. Therefore, the correct construction is "Our country is spiritual; theirs is religious." Option A correctly provides the singular form of the verb "is" to ensure parallelism and subject-verb agreement.