Leading a life that is not authentic and does not reach its potential?
Without a believe in a higher power there is no technical "purpose" to life therefore technically no way to describe "full potential."
It could very well to live a good life and to be happy to many people. Being a christian, as long as one is tolerant of others, is a fine way to accomplish that goal for many people. For others it is to seek ultimate truth and answers about the universe, or contribute in science in some way. To others it would be help as many people as possible.
The poster said that the Bible is what they believe because its the best offer they have seen. A conscious choice has been made there and it is not dillusional or dangerous. Even if it turns out to be wrong, maybe its the best choice for them. I wish all christians so answered.