A method for diagnosing and treating an immune microbial dysfunction in a subject, the method comprising: receiving an aggregate set of biological samples from a population of subjects; generating at least one of a microbiome composition dataset and a microbiome functional diversity dataset for the population of subjects; generating a characterization of the immune microbial dysfunction based upon features extracted from at least one of the microbiome composition dataset and the microbiome functional diversity dataset, wherein the characterization is diagnostic of at least one of Crohn's disease, inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), ulcerative colitis, and celiac disease; based upon the characterization, generating a therapy model configured to correct the immune microbial dysfunction; and at an output device associated with the subject, promoting a therapy to the subject based upon the characterization and the therapy model.