My identity is in Christ, but sometimes my identity gets misplaced in other, less secure things.
For a while, my identity was in my diet. I was vegetarian and proud. After a while, I was a vegetarian out of habit and that part of me was more important than my obedience to God. He reminded me that I am a Christian first. I started eating meat again when I headed to the mission field for a 2 month stay. Now I cook vegetarian sometimes, but not excusively.
For a while, my identity was in my grades. I am smart and my grades reflected my intellect. It was hard for me to adjust to a college level history class, where I was expected to write essays instead of taking multiple choice tests. My ego took a blow when I got a B in History freshman year, but I still prided myself on my As and that one B. When I hit hard classes, I had to work harder, but I still made my As. Then I hit the science of sound. The physics of music. I'm not a science major...or a music major. For a while I was sure that I would get a C in the course. It was a horrible blow to my ego and I had to readjust and remind myself that my identity is in Christ, not in my grades.
Then my identity switched to my "no cavities" history. It turns out that my memory was faulty and I had had prior cavities, but I still placed my identity in my false cavity free past. Then I had a cavity and I had to readjust and realign my identity to Christ again.
These identity crises took place in my sophomore, freshmen, and senior years of college respectively. Time and time again, I place my identity in something other than Christ and then am shocked with my identity collapses because it wasn't in something solid.
Christ is the solid rock. When my identity is in Christ, it is solid. It is stable (yet growing). When my identity is in the solid rock, I'm secure and correctly identified.