Jesus is reported to have said, “strait is the gate, and narrow is the way, which leadeth unto life, and few there be that find it.” From that passage, we get the phrase, “the strait and narrow,” not straight (like the path of an arrow), but strait (meaning a narrow entryway, like the Strait of Gibraltar). The way you spell strait makes an enormous difference to the way we understand the Christian life! If you think that the Christian path is a straight one (like the path of an arrow), you might get the idea that the Christian life is a simple matter, straightforward, but with temptation on either side. All you have to do is learn it, and then any change in direction means deviation from the path, sort of like Dorothy following the yellow brick road to Oz. Unfortunately, this way of thinking of the life of faith can lead to rigidity, arrogance and self-righteousness, all things that Jesus warned against.
There is another symbol that may offer a more helpful way of thinking about the spiritual life. According to this symbol, the Christian life is more like walking a twisting, turning path. One ancient symbol of such a narrow winding way is the labyrinth.