There are certainly a variety of scholarly perspectives as to the structure of 1 Timothy 3.16.
Some perceive the text as consisting of a pair of triplets of meaning (e.g. – GNT). Others see the sentences as expressing three consecutive pairs of thought (e.g. – NLT). And there are other understandings, as well.
However, I subscribe to the chiastic point of view. This view seems to me to be made most obvious in the easy-to-read edition of the NIV known as the New International Reader’s Version (NIRV) for it makes especially clear the pairings of thought between (1) matters connected with earth/visible/flesh and those connected with (2) heaven/invisible/spirit.