Most of us approach Spirituality, the journey of sanctification, as if it is linear. You are travelling across an open plane, getting from point A to point B, and since the fastest way to get anywhere is a straight line, we think our Spirituality should be a straight line. Which means we shouldn't ever visit ground we have already visited, or zig zag along the way. That is all wasted motion, it is all wasted effort that means we are following Christ wrong.
Put another way, we approach following Jesus as if it is like school. In school you take a class, you pass that class, and then you move on. You take Geometry, you pass geometry (if you are smart!), and then you don't take geometry again. Oh, you might take another math that somehow relies on geometric principles, but it is not the same class. It is harder, more advanced, more complex. And if you do end up taking geometry again, going over the same lesson about proofs another time... well that means maybe math isn't your thing. If you take geometry ANOTHER time after that, again going over that tricky lesson on proofs... well maybe you aren't the sharpest tool in the shed (or perhaps really lazy?).
That is all well and good for geometry. But we mustn't think of Christian Spirituality that way. If you think that on the path of following Jesus you take classes "Loving Others 101", "Faith in Jesus", and "Loving God and Not the World" and then after taking them move on to higher more advanced subjects... you are in for a rough surprise. You will get discouraged as each time you think you "learn the lesson about faith" somehow or other you find later on that you are right back in the same situation, learning the same lesson all over again. Once or twice in the remedial course and you can hype yourself up and convince yourself you wont be back.. but after your twelfth time learning the lesson "God is greater than you" or "Love God and Others, not yourself", well it is hard not be down on yourself or think of giving up. "Will I ever learn ANYTHING?! I thought I already learned this!"
But all of that is unnecessary. Following after Jesus isn't like walking across an open plain or taking secondary courses. Following Jesus is like climbing a mountain. When you cross a plain, you walk straight and thats pretty much it. When you climb a mountain you go up and down and side to side, and all of that is moving you forward. When you climb a mountain there are switchbacks-- you move back and forth between the same exact points, moving upward. Though in one sense you are on the same part of the mountain you have been on before, in another sense you are not: you are higher up. And how do you move further up the mountain? By returning to the very same spot on the mountain, just a little higher up.
Christian Spirituality isn't linear. It is a spiral. In a line you move forward by never coming back to the same ground. In a spiral you move forward by covering the same ground over and over again, just a little higher up each time. I think this is how God shapes us.
And doesn't this make sense after all? We have all found ourselves back "relearning" a lesson we have already learnt before. This isn't because we are stupid or spiritually stubborn or that we didn't learn the lesson the first time. It is that the last time we learned the lesson we weren't mature enough to learn all of it. We weren't sanctified enough to learn any more than we did, and we probably weren't even able for God to reveal more about our depravity to us. Each and every time we revisit the same ground and learn the "same" lesson, we see it from the slightly higher position of our growing maturity. What does this mean?
You never get past the basics of Christianity. You will never leave behind the lessons of faith and hope and love. They are what holds everything together. You never get past the gospel. It is something you never stop learning, in a thousand different ways at a million different times all along the path toward He who is the Head, the Lord over all, Christ.