The doctrine of election/predestination is one of the most debated issues among pastors and theologians. Some can accept it because there is clear evidence in the Bible. Those who reject it say this teaches that God violates our free will to choose. I know for me this doctrine was hard to accept at first because of my Southern Baptist background and the fact that I was not around teachers to help me understand the doctrine.
This have been many misunderstandings regarding predestination, but I think there is one that stands out among them all. That misunderstanding is this: Predestination means that God saw in the future those who were to saved and elected them based on their faith. Some may say, "What is wrong with that statement?" The answer is this is not predestination.
Yes, God does know the future and those who are His (2 Timothy 2:19). He knows in the end who will be with Him for all eternity, but that does not mean God opened a time portal to see who would put their faith in Him and grant them grace. If that is true, then we are not saved by grace. Ephesians 2:8-9 says we are saved by grace through faith and it is not from our own doing. Normally we think of good works as our own doing, but in this case it also includes faith. We are saved by faith, but God does not determine His sovereign choice based on one's faith. God saves those because He is a God of grace and mercy. The Bible says, "'I will have mercy on whom I have mercy, and I will have compassion on whom I have compassion.'" So then it depends not on human will or exertion, but on God, who has mercy" (Romans 9:15-16).
The doctrine of predestination is one of great mystery and always will until we Jesus face-to-face. We should not lose heart if we don't get it at first or never will understand it 100%. I was amazed that John MacArthur once said, during a discussion on election, that he still has questions and struggles over the doctrine of predestination. There are some that may ask, "How do I know if I am part of the elect?" Here is what I say, you truly believe that Jesus is the Savior of your sins and you see the regenerative work of the Holy Spirit in your life. Odds are you are part of the elect.
There are many good resources out there on the doctrine of election. Here are just a few:
What is the Doctrine of Election? from Grace To You
Chosen for Life: The Case for Divine Election by Sam Storms
Chosen By God by R.C. Sproul
The guys over at Doctrine and Devotion recommend this one, but I have not read it yet: The Reformed Doctrine of Predestination by Loraine Boettner