Agreed. I always believed that the concept of overcoming and growing in faith was a basic tenet of Christianity. Imagine my surprise when I discovered that a large segment of Christians don't subscribe to that view.
One method I've seen taught to discern between initial faith and a mature faith has been an association of initial faith with a salvation faith and a continuing walk, further filling of the spirit by doctrine (doctrine being the meaning of PISTIS in continuing post-salvation sanctification).
When reading the 1Co 10:1-5 passage in the Greek New Testament, I'm amazed at the migration from SOMA to BROMA to POMA all being associated with PETRA of CHRISTOS. The passage seems much more poetical is the original Greek. It also provides enormous insight. One of the more beautiful passages I've read.