But as readily as we grant this, it should be maintained with equal stress and emphasis, that this does not exhaust the knowledge of God; that it contains a spiritual reality which goes deeper than intellectual acumen, and employs the abstractions of dogma and doctrine merely as a means by which to clarify impressions received, the perceptions of the soul and spiritual experience.
It means that the aspects of "knowledge of God" that are described in the preceding paragraphs are not all the knowledge of God that is possible. Those are not "exhaustive" descriptions.
American Heritage Dictionary "exhaust"
tr.verb 3. To discuss or treat completely; cover thoroughly: exhaust a topic.
The previous paragraphs can be seen here;
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