“Will some Christians be left behind?”

My pastor told me that 70% of church members will be left behind at the rapture because of their ungodly living. Could this be true? I keep repenting and asking forgiveness for telling funny stories and cutting up. I can’t seem to stop, and I wonder why I’m in this cycle. Can you help? An elder at my church said I need to focus on my recent sins at the Lord’s Supper. He quoted from 1 Corinthians 11 about eating and drinking in an unworthy manner. What does that mean?