My beef with Calvinists is not that they believe they were elect from the foundation of the earth, heck I believe that, it's that Calvinists believe that if you don't believe that you were not given a choice in the matter -- despite all the verses that say that you do have a choice in the matter -- that somehow you don't believe the Gospel and that your "gospel" is the lie of Eden or some other such nonsense.
I believe that when God says "Choose Life, that you might live" that he really expects people to make that decision for themselves. God does not make the decision for you. If you go to hell it is because of missed opporunities, not because God gains pleasure from sending people there. It is in that sense that I see Calvinism as dangerous. Not because they believe that regeneration preceeds faith.