Surah a non-believe should read?

Hi, so I have a friend who is a non-Muslim, but his family background is somewhat Muslim—his dad is an atheist, and his mom is Muslim. He’s a smart guy, Allahumma barik, and we often talk about topics related to the purpose of life, finding one’s vocation in this world, and discovering what one truly loves doing.

He’s the type of person who goes through the motions of life and is generally content. I feel like, unless he experiences a major event or change that makes him question his purpose, he may never deeply reflect on the bigger questions—Why are we really here? Am I truly content with what I’m following in life? (i.e., desires as one’s “god”).

We’ve discussed Islam countless times, and he has even fasted with his family for several years. However, he seems hesitant or perhaps even afraid of major change. One of his biggest concerns about Islam is the Prophet’s (ﷺ) marriage to Aisha (RA), which he views through a modern lens as problematic. Another major question he has revolves around Qadar (divine decree) and free will.

My main question: What is one Surah you would recommend to a non-believer who is content with life—one that would make them contemplate the Hereafter and their true purpose (submission to the will of Allah)?