If you are, how do you know you are a Christian? Is it possible that true believing Christians might not make it into heaven? Checkout what Jesus is supposed to have said:
[Matthew 7:21 (New King James Version)]
21 “Not everyone who says to Me, ‘Lord, Lord,’ shall enter the kingdom of heaven, but he who does the will of My Father in heaven.
If this is true, then it is possible that many people who think themselves Christians are simply wasting their time, for they might be turned back at the pearly gates by the master they so sought and praised in their lives. What a way to waste ones life.