A "highest point" is the topmost level or peak of something, like a mountain or building. It can also mean the maximum stage or most successful moment in an activity, career, or process.
This is the highest point of philosophy, to be simple & wise; this is the angelic life. John Chrysostom
If you do not raise your eyes, you will think you are the highest point. Antonio Porchia
The highest point a man can obtain is not Knowledge, or Virtue, or Goodness, or Victory, but something even greater, more heroic and more despairing: Sacred Awe! Nikos Kazantzakis
Man reaches the highest point of lovableness at 12 to 17 - to get it back, in a second flowering, at the age of 70 to 90. Karen Blixen
The highest point of Christian experience is to press forward. It is a distinguishing trait in the character of every good man that he grows in grace. Grace in the heart as certainly improves and advances, as a tree thrives in a kindly and well watered soil. Gardiner Spring
Man reaches the highest point of his knowledge about God when he knows that he knows him not, inasmuch as he knows that that which is God transcends whatsoever he conceives of him. Thomas Aquinas