THE QUESTION IS A PARLOR TRICK BUT I WILL TRY TO DO IT JUSTICE – MORE JUSTICE THAN IT DESERVES. 🙂 OBSERVABLE TYPES OF LOVE
As far as we know, humans demonstrate these kinds of love, from the most intense to the least intense.

  1. Erotic love ( sexual attraction with the potential of joining the family)
  2. Familial Love ( members of the family – decreasing with genetic distance)
  3. Friendship Love ( treat as family even though not )
  4. “Christian Love” ( Treat as family for social and economic purposes. More recently referred to as “unconditional love”.  But which, at least, biologically and scientifically, means the extension of ‘familial love’ outside of one’s children.)

The success of the theistic religions has been to create conditions by which familial trust (love) is extended to non family members.  THis allows social and economic cooperation at scale. It is an interesting ‘trick’. A very useful device. It was very successful at uniting (poor) tribes into larger national and cultural units with similar ethical, moral, and legal codes.  WHile we may argue that the allegorical and magical nature of most religions is logically absurd, it is not necessarily illogical that religion has been demonstrated to be the most successful means by which to aggregate people into common ethical, moral and legal structures.

THE HIGH TRUST SOCIETY
The west achieved it’s High Trust Society status by forbidding cousin marriage out to six, eight or even ten generations, and extending property rights to women. By those two acts, over time, in fact, all people within a region were either near genetic relations, or had the possibility of becoming near genetic relations.

THE FAILURE OF THE RELIGIONS
This is why the west was more successful than any other culture at extending not just ‘love’ but property rights and economic cooperation to all members of the community.  Other societies may have succeeded in extending interpersonal treatment of others beyond family boundaries, but they were unsuccessful at extending property rights away from the paternal family or the totalitarian state.  Because of this, other ‘religious love’ actually was destructive to the economic, social, legal, and political development of those countries. It prohibited rather than encouraged a division of labor into specialization, and the concentration and coordination of capital into the production of consumer goods..

THE FAILURE OF SECULAR HUMANISM
Secular humanism, or Totalitarian Humanism, like it’s ancestors Postmodernism, Scientific Socialism, Socialism, Marxism, Christianity, and Judaism, attempts to regress western civilization’s emphasis on private property and public actions by returning us to totalitarian management of property as a commons, and forcible rather than voluntary charity.

THE SHORTAGE OF USEFUL ‘RELIGIONS’ (Myths and Rituals)
Religions can work if they support production and private property as did protestantism.  The problem is that only greek and german hero-worship and perhaps Shinto, other than protestantism, are compatible with the retention of property rights and individualism.  The American Constitution, the English Common Law,

But then, this is one of the great problems of human history and we barely understand it.

https://www.quora.com/Can-atheists-fall-in-love-If-an-atheist-does-not-believe-in-God-because-they-need-proof-can-they-fall-in-love-which-presumably-also-cannot-be-proven-And-if-so-how-do-they-know