Seeing that the Lord made Regeneration (the New Birth) mandatory for entrance to the Kingdom of God, it is something that all Christians should understand thoroughly. One of the best ways, in my view, to teach on this matter is to ask this question, "Were men born again before Pentecost?" In the years I have been debating this I would put the responses at 95% say yes, the rest say no. So before you answer this question give it a little thought, because if you have not given it thought before (and many haven't) it might be you are in for a surprise. And if you don't mind please mention whether this is a question you have given thought to before.