Side line: “kata sarka” (according to the flesh) must be taken as adverbial, it qualifies verbs for “knowing” – how they know or in this sense not knowing – “not according to the flesh.”
「凭血」(
﹕凭外貌;意思﹕凭肉体)﹕是副词,指「
道」、「认
」人这动词。他们如何认
(
认
)﹕「
凭肉体」。