Don't confuse the gospel with religion
To prevent doing this, talk about Jesus (who he is and what he has done) all the time. If you don't, students will think Christianity is really about something else, like morality, philosophy, piety, social justice, or a religious experience. If you start talking more about what they should do instead of what Jesus has done, you're preaching another gospel (Gal. 1:6-9), which is to put heavy burdens on them (Matt. 23:2-4).