While unbiased statistics on the issue are hard to come by, the general perception of many Christians is that most of you high school students will "walk away from their faith" soon after walking across the graduation stage. In short, my challenge to you is simply this: Prove them wrong! However, I also realize the reality of the issue and the many changes, pressures, transitions, expectations and responsibilities that all come into play during this time of your life.
For those continuing your education in college, there is more freedom as you may not have teachers taking attendance or making sure you're doing your homework. Your parents likely aren't going to be telling you to go to bed or clean your room. Classes don't take up your entire day and you might even have entire days without class at all. Some classes don't really have assignments, only midterms and finals, which makes it more difficult to force yourself to study. In order to pay for college you'll likely find a job in addition to your classes and social life. You may be making new friends or figuring out how your relationships are shifting with old ones. Suddenly, it sadly makes sense in all of this that someone's focus on God could easily fade.
While God's people haven't always had something like college to go to, the concept of transition is nothing new. What I notice throughout God's Word and the world around me is that life changes definitely create movement in our relationship with God. For some, those changes draw them nearer to God while others find themselves walking farther and farther away.
Take Job for example. Within the course of one day almost his entire family, servants and livestock are destroyed, and his wife isn't much help as she tries to just get him to curse God and die (see Job 1-2). All through the 42-chapter struggle, we see Job continue to seek God and by the end, Job is closer to God than ever before and understands more about God than he could have imagined.
Others found themselves turning the other direction when life transitions arose. This includes the Israelites Moses brought out of Egypt. God saved them from having to be slaves forever. He divided the Red Sea and was providing all they needed. Yet they complained and disobeyed, walking farther away from God as they walked for years in the wilderness (see Exodus).
The amazing thing to remember in all of this though is that God goes with us in the transitions and even when we, like the Israelites, wander away, our God seeks after us, saves us again (and again and again and again) and restores our relationship with Him, just like he continually did with the Israelites.
While the hope and prayer is that the pressures of life after high school would draw you near to God for wisdom, guidance and hope, we can "know and rely on the love God has for us" (1 John 4:16) trusting that even if we wander away, His love remains. Above all, never forget the truth of God's love and the abundance of His grace, to forgive again and again and again. May you live in that love and share that love every day whatever life after high school brings.