Humans and many other organisms have evolved pleasure-pain mechanisms. To the extent that any evolved capacity can have a "purpose," the purpose of pleasure is to guide us towards those actions that preserve our health. The evolutionary "purpose" of pain is to warn us away from harmful actions. Pleasure and pain are our headlights illuminating a sometimes brutally dark and dangerous world.
Humans, however, can hold values higher than pleasure. We can place civility, honesty, bravery, loyalty, love, compassion, and many other values above pleasure. We can do this because we have evolved free will; we have evolved the ability to guide ourselves, even when swimming against the stream of electrons flowing through our biological pain-pleasure wiring.
But we still rely on headlights. These "higher" values don't come into our brains out of thin air. Aside from a few twists we as individuals add to them, aside from an innovation here and there, and aside from how we apply them to our unique individual lives, the basics of our values have been conditioned into us by our cultures.
Evolutionists have long noted that culture itself is an outgrowth of evolution. Cultures evolve out of our drive to avoid pain and pursue pleasure. By which I mean: Cultures are ever-evolving repertoires of tools for survival and prosperity. Less useful tools are usually dispensed with during the course of cultural evolution, the same way species lose features that ill-suit them to their environments. Sometimes, as we all know, cultures create and preserve harmful practices. In the same way, the pleasure-pain mechanism is not infallible.
So our cultures have evolved these "higher" values. And these higher values, on balance, serve us well. Religions play a role in creating and maintaining values that "transcend" pleasure and pain. But in fact the healthy religious values don't transcend the pleasure and pain mechanism at all. Healthy religious values extend the range of the pleasure-pain headlights further into the darkness.
Take the Christian virtue of love. Jesus is said by the Bible to have replaced the punitive commandments of the Old Testament with a value system based on only three new commandments: 1) Love God with all your heart; 2) Love your neighbor ... as you 3) Love yourself.
We can question whether Christianity originated the concept of a higher, spiritual love. We can also question whether Judaism, out of which Christianity sprang, originated a higher love value either.
But it's pretty hard to argue with the fact that sacrifice plays a central role in the Christian conception of spiritual love, and in the love-conceptions of many other world religions. The bulk of the New Testament deals either directly or indirectly with the significance of Jesus' sacrifice on the cross. Jesus held that this sacrifice was done out of love for us sinners, and it is clear from the New Testament that Jesus taught the importance of sacrificial service. Leaders in the Christian system are ideally not those who promote themselves, but rather those who serve.
I think it's fair to say that Christianity's central tenets, so far as they apply to secular life, can be summed up by saying that Christian love is achieved by sacrificial service. During one of the most important Christian rituals, communion, Christians are told to take the bread and wine in remembrance of Christ's sacrifice for us. At the same time, the bread and wine are viewed as "the body and blood" of Jesus Christ. Bread and wine are spiritual food to Christians, who are also viewed as members of Christ's body. Christians therefore fill themselves with self-sacrificial love, with the essence of Christ, when taking communion.
It might be argued that Christianity didn't invent this conception of love either. Sacrificial offerings for the sake of connecting to Divine Love date back to well before Christianity. That doesn't matter for my purposes. All that matters is that in most cultures, the greatest advocates for sacrificial love have usually belonged to one religious tradition or another. This applies to love of Higher Powers, interpersonal love, and love of one's own Divine humanity.
My punchline is this: Sacrificial love does not imply painful love. Pain can sometimes be involved. Adding sacrifice, and the possibility of pain, to the equation is one respect in which religious love modifies the pleasure-pain mechanism as a guide to action. But for the most part sacrificial love and pleasure are complementary. They fit each other the way batteries fit a powerful flashlight.
That is, for the most part love - even when it involves sacrifice - brings some kind of happiness, satisfaction, comfort, or other enjoyable feeling.
Defining love is a notoriously intractable problem. Nonetheless the positive effects of what most people can agree on as actualized love can be seen all around us: rewarding interpersonal relationships, beloved children nurtured by caring teachers and parents, charitable organizations, beautiful works of literature and art and monuments inspired by love ... It's not hard to make a long list of the ways love helps humans to survive and prosper.
Thus love is a cultural value that furthers the interests of humanity. Throughout history, religion has been more responsible than any other cultural institution for propagating this prosperity value. Love evolved from the pleasure-pain mechanism. Love is a guide to action. Religion added to the guidance of love the further guidance that self-sacrifice is the power source for the bright guiding light of happiness love gives us.
Thus religious self-sacrificial love is not properly understood as the denial of earthly pleasures. Asceticism is largely a perversion of religious love. Rather religious self-sacrificial love - and romantic self-sacrificial love, and paternal love, and just plain love - are steps on our long evolution from beasts of fate, scratching mere subsistence out of the mud, to happy, self-directing spiritual beings.
