I'm with you

In experience and thought. I have also left the Catholic Church, and yet the two best Christians I have ever met were both Catholic.

If Paul was worried about "finishing the race" we should be as well.

With respect to the certitude that many profess, Richard Rohr said it well:

In the Franciscan worldview, separation from the world is the monastic temptation, asceticism is the temptation of the desert fathers and mothers, moralism or celibacy is the Catholic temptation, intellectualizing is the seminary temptation, privatized piety and inerrant belief is the Protestant temptation, and the most common temptation for all of us is to use belonging to the right group and practicing its proper rituals as a substitute for any personal or life-changing encounter with the Divine.

Rohr, Richard (2014-07-27). Eager to Love: The Alternative Way of Francis of Assisi (p. 5). Franciscan Media. Kindle Edition.