John Piper said, “The book of life represents God’s free and unconditional election. In the New Testament the book of life is synonymous with the list of those who are elect and predestined for eternal life.” John Calvin said, “Those, therefore, whom God passes by he reprobates, and that for no other cause but because he is pleased to exclude them from the inheritance which he predestines to his children.” (italics added)
The inflexible truth is, if one is true to Calvinism, he cannot look into the eyes of any and every individual and say God loves you and Christ died for you; God wants you to be saved, and you can by the grace of God be saved if you will only trust Christ (John 3:16). Thus, one cannot be a Calvinist unless he believes that the Scripture teaches the Calvinist’s claims that God does not salvifically love everyone enough to actually offer forgiveness, Christ did not die to pay the penalty for everyone’s sins (in a meaningful way so that now they are free to actually be saved because of such work), God did not provide grace for everyone to exercise faith in Christ and be saved, and people are in hell because it pleased God to withhold what would surely have delivered them from that torment.
Although many Calvinists seek to distance themselves from the belief in double predestination, there is actually no room for any other belief within consistent Calvinism. It is true that all sinned, and all deserved hell; thus, Calvinists are correct to claim that God would have been just to damn everyone.
However, the fact is that He did not so choose. He did in fact freely choose to elect only some when He could have just as easily chosen one more, or everyone, without performing any other redemptive work. Further, He was, and necessarily had to be, equally aware of the ones He was choosing to arrive in heaven, and the ones He was not choosing to arrive in heaven, and that such choosing predetermined the destination of the non-elected as certainly and knowingly as it did the elect.
Therefore, the deciding, predetermining, factor of why someone is in heaven or hell is, and can be only God’s choice, which is the essence of unconditional election–the real deciding doctrine of whether one is a Calvinist or not. Such means that every disavowal of double-predestination made by Calvinists is ultimately obfuscatory rather than explanatory. This is a disquieting reality.
Although I recognize some Calvinists do understand and readily accept these realities, I am also aware that many who identify themselves as Calvinists are either unaware of or do not fully understand these essential bedrocks of Calvinism. Additionally, many further becloud such entailments of Calvinism by speaking, either wittingly or unwittingly, inconsistently with these inescapable beliefs of Calvinism. This conclusion is not merely hypothetical, but rather it is based upon personal experience of having been a Calvinist as well as reading and engaging Calvinists for thirty years. Such inconsistencies are easily gleanable from the speech and writings of both knowledgeable and theologically unsophisticated Calvinists.
 http://www.desiringgod.org/resource-library/taste-see-articles/late-night-meditations-on-the-book-of-life, accessed 4/9/11.
 John Calvin, Institutes of Christian Religion, Book 3, Chapter 23, page 226.