Ephesians 1

Just as He chose us in Him before the foundation of the world, that we should be holy and without blame before Him in love, having predestined us to adoption as sons by Jesus Christ to Himself, according to the good pleasure of His will. vv.4-5

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Predestination.  Do you believe it?  Well maybe that's not the right question.  Yes the word predestination is in the bible, but what people don't realize is that it is not used in regards to being predestinated for salvation.  To start with we must realize that foundation of the world doesn't just mean the time of creation of the earth.  Yet when we understand the difference of the use of foundation and world instead of creation and earth we will realize that this is talking about the world that God will found in the future: the Kingdom.  

Thus we who are saved are chosen by Him to be holy and without blame before Him in love. This choice is made in the time we live before the foundation of His Kingdom world. Yet this choice is not made before we believe. Rather, it is made afterwards, when “we” who are saved are “chosen” to experience this in the future. By grace based on our faith we become one of these chosen. Yet we were not destined to become one of these chosen before the earth was created. That is not what this passage means! (Nathan Johnson, Bible Teacher)

The book of Ephesians we must also realize is written to already believers, "To the saints who are in Ephesus" (verse 1).  When it says they are predestined to adoption as sons it means that once they become believers they inherit the benefits of being God's son or representative according to the Greek word huios.  Once one becomes a believer their predestined to take on God's characteristics in representing Him, nothing about salvation.  

To be a son is not at all the same thing as being a child. A son is a representative of his father and takes on his father’s character. So what this verse is teaching us is that we are predestined to be adopted as sons by Jesus Christ. That is, we are predestined to take on His character and His attributes. That is far different than us being predestined to become His children. This would not be true. We become His children by grace through faith. We are not predestined to this. This passage is again talking about believers, and telling us that we are predestined to take the place of representative sons of God in the future. This passage has nothing to do with anyone being chosen in advance to be saved. (Johnson)

So how might this change or help you understand predestination?  For more articles on predestination or Calvinism check out Calvinism