A common objection to the doctrine of unconditional election (aka, predestination) is John 3:16. I typically get bent out of shape whenever I read or hear people using this verse as an objection to predestination, and not because it blows a hole in my theology, but because it is a mishandling of the Word of God to use it in such a fashion. I am currently reading R.C. Sproul's Chosen By God, and he has an excellent treatment of this common usage of John 3:16:
What does this famous verse teach about fallen man's ability to choose Christ? The answer, simply, is nothing. The argument used by non-Reformed people is that the text teaches that everybody in the world has it in their power to accept or reject Christ. A careful look at the text reveals, however, that it teaches nothing of the kind. What the text teaches is that everyone who believes in Christ will be saved. Whoever does A (believes) will receive B (everlasting life). The text says nothing, aboslutely nothing, about man's natural moral ability. Reformed people and non-Reformed people both heartily agree that all who believe will be saved. They heartily disagree about who as the ability to believe.The doctrine of election has nothing to do with belief in Christ as the basis for eternal life. It concerns itself with who exactly will believe in Christ, and thus inherit eternal life. There will be no soul in Hell who professed faith in Christ, but was denied everlasting life because he was not one of the elect. True faith in Christ always saves and is itself a sign of God's adoption of you as his son or daughter. The true debate, as Sproul points out, is about who has the ability, the desire, to believe.