First of all “the couple” do not unite in the Heart, one “only” sees into the Soul in the Heart. Seeing the Soul, blissful as that is, may help us identify the goal of the Spirit, which is Godhood, but Godhood can be reached only through material evolution all the way to the materiaspiritual, and ultimately to God. Thus evolution is not a “nightmare,” it is seen as a nightmare when the involutionary, internal methods of religion reduce Godhood to the Soul-Within.
We require both the involutionary methods of religion and the evolutionary methods of nature and science, first to see God, and then, with God's Grace, to reach God. Both methods are applied in the Evolutionary Christian Church.