What is Christian erotic romance? In short, a romance whose
(1) theme is influenced by and/or illustrates the teachings of Jesus of Nazareth as found in the New Testament gospels and/or the teachings of his disciples as found in their New Testament epistles and histories.
(2) is written at the no holds barred sensuality level the romance genre calls erotic
(3) Usually, but not always, has a Christian as its protagonist or antagonist and even at times, the villain.
Like it's cousin -- inspirational romance -- the faith arc is a defining element in Christian erotic romance. God is in the mix. This is why -- IMHO -- love in both Christian erotic romance and inspirational romance is always a threesome or, in the case of a menage, at least at threesome.