Islam as a tree vs. Islam as a pillar

Although I cannot call myself an expert on Islam (even though I pretend to be), I have read many books of various types on Islam: sanitized or faith-promoting histories of Islam, historically accurate histories of Islam, believers’ discussions on Islamic beliefs and theology and practices, outsiders’ discussions on Islamic beliefs and theology and practices, etc. From what I have learnt, in my mind I depict Islam as a tree. The stout trunk is the foundation laid by Muhammad and the early conquerors of Islam. From this trunk various branches have come forth, some thicker than others, some healthier than others, some that exist and some that have fallen off. These branches are interpretations and applications of the foundation (trunk), making a wonderful, large, beautiful tree with many types of flowers and leaves.

I shared this with a cousin of mine who is trying to understand Islam, but he was unhappy. As a believer, he views Islam as a pillar: one truth, one interpretation, one application, one ummah, one faith. He sees other interpretations and applications and practices as elements that weaken the pillar and make it less beautiful. But, he asked, which of the many interpretations of Islam is the right one?

I like my view because it allows me to appreciate the diversity of Islam. But I am not a believer, so I can live with that. I can understand the frustration that believers may have, what with Islam acting like a tree but supposed to be a pillar.

First, which view is most correct of the reality of what Islam is and what it claims to be?

Second, is there any way to determine which interpretation is the “right” Islam?

WRS - La ilaha ill Allah . . . but what does it really mean?