Faith is defined as
a firm belief or
high confidence or
complete trust in
In the Bible, faith is defined like this: "Now faith is the substance of things hoped for, the evidence of things not seen." (Hebrews 11:1, King James Version)
As we consider those two conceptions of faith, it is abundantly clear that teaching is an act of faith. Perhaps we could call it the ultimate act of faith.
I know, and have been the beneficiary of, many wonderful teachers. Not all of them have been professional educators (though many have).
Each of those teachers, whose "fingerprints" have been left all over my life, invested in me and engaged with me, acting in faith. Faith that the knowledge, or the skills, or the ways of thinking they were sharing would find purchase with me and would ultimately bear fruit.
If teaching is an act of faith, then LEARNING is the evidence of its exercise.
"...the substance of things hoped for..."