Denial of the gospel at death, but even then we aren't completely sure in every case. If you had read my first post on this thread, it would clear most confusion up.
Do I know that I am an elect? Well, it is the same question as do I believe and remain abiding in the person and work of Jesus Christ alone for my salvation to and reconciliation with God? Only the elect come to embrace Christ. But even then, the apostle warns us to "be all the more diligent to confirm your calling and election" (2 Peter 1:10), and so it sobers us to examine ourselves to see if we are in the faith.
Do I know that I am an elect? Well, it is the same question as do I believe and remain abiding in the person and work of Jesus Christ alone for my salvation to and reconciliation with God? Only the elect come to embrace Christ. But even then, the apostle warns us to "be all the more diligent to confirm your calling and election" (2 Peter 1:10), and so it sobers us to examine ourselves to see if we are in the faith.