"The rest of mankind that were not killed by these plagues still did not repent of the work of their hands; they did not stop worshiping demons, and idols of gold, silver, bronze, stone and wood—idols that cannot see or hear or walk. Nor did they repent of their murders, their magic arts, their sexual immorality or their thefts."
The heart of man is desperately wicked even unto the end of the world. It is a sad reality we must realize that some men and women will die in their sin because of their stubbornness and hardheartedness. These people are seeing but never perceiving, hearing but never understanding lest they turn and be healed. Goats cannot be turned into sheep anymore than weeds can be wheat, but Christ knows the difference and will sort them out in the last days.
So what is the difference? The elect, upon hearing the truth of Jesus Christ, will love him for they know the voice of their master intuitively. However, the rejected will resist Christ and his gospel until the day they die.
So how can you tell if you are elect? All of the elect want to be elect and all of the rejected could care less about Christ and his gospel. So if you want to be elect, chances are that God has already chosen you from before time began to be elect and has instilled in you the desire to follow Christ. All that's left is to actually follow Him.