Check out verses 19 - 22. I think that, growing up, I had this sort of concept that, once you accepted God, you were "in". Over the years, I have come to understand that you must maintain your belief, your faith, and your pursuit of God. I have also come to understand that, out of our love for God flows a desire to "give back," to do good for others. These verses make it very clear that we can, through out own actions or perhaps lack thereof, cut ourselves off from God. A great thing for me to be reminded of now as I resolve to be better in my daily discipline.