Continuing on with my look at the Biblical term "elect," the first 'controversial' text I want to look at is Romans 8:33 where Paul famously asks: Who shall bring a charge against God's elect? Before diving into that, it's important to recall what the Biblical term "election" (and "calling") refers to, particularly that the Bible doesn't use it to refer to someone who is unconditionally elected to make it to heaven. With that, we can quote the context and I'll present my case for "who" Paul has in mind here.
32 He who did not spare his own Son but gave him up for us all, how will he not also with him graciously give us all things? 33 Who shall bring any charge against God's elect? It is God who justifies. 34 Who is to condemn? Christ Jesus is the one who died—more than that, who was raised—who is at the right hand of God, who indeed is interceding for us. 35 Who shall separate us from the love of Christ? Shall tribulation, or distress, or persecution, or famine, or nakedness, or danger, or sword? 36 As it is written, “For your sake we are being killed all the day long; we are regarded as sheep to be slaughtered.” 37 No, in all these things we are more than conquerors through him who loved us. 38 For I am sure that neither death nor life, nor angels nor rulers, nor things present nor things to come, nor powers, 39 nor height nor depth, nor anything else in all creation, will be able to separate us from the love of God in Christ Jesus our Lord.
This passage is often read by Protestants (typically Calvinist/Reformed types) to mean that the Christian is Eternally Secure. That no sin can separate us from God. Catholic apologists are right to point out that this list of dangers which Paul lists are not sins but rather persecutions. This is important because it means Paul is not at all saying that "no sin can separate us," because the fact is sin can separate us from God. That's the whole point of Adam & Eve falling into sin. They were in communion and the fell from communion with God. (I've not really heard a coherent explanation from Protestants as to how Adam & Eve could fall from communion with God if salvation is eternally secure.) What I want to do here is go one step further.