Many Christians try to "sell" Christianity based on the idea that it is focused upon an instance where God and humanity became one. This is supposed to special and unusual among religions; in reality, though, many religions have found ways to fuse the human and the divine. Hinduism, for example, not only has its own tradition of unions between humanity and God but also they occur far more often. Why would anyone think that this something that only occurs in a Christian context?
In Hinduism, Vasudha Narayanan writes:
Perhaps more than any other religious tradition, Hinduism recognizes divinity in human beings. Many spiritual teachers are considered to be souls who have ascended to be one with the supreme being; others think of holy men and women as the descent of the divine being to earth. For some disciples, the teachers are even more important than God. The Upanishadic dictum (Taittiriya Upanishad) to treat your teacher as God is well known by millions of Hindus.
On the one hand, opening the possibility for anyone to be become "one" with the "supreme being" may be thought of as fundamentally egalitarian in nature. That's certainly how Christians try to portray it, arguing that the presence of a "spark" of the divine in every person means that what we do to each other is, in effect, what we are doing to God. No one person is inherently better than any other because we all partake equally in this divine "essence."
In Hinduism, however, it also opens up the possibility of everyone interacting on a personal level with their God, an option closed off to Christians since the presumed death of Jesus. Granted, evangelical Christians talk about having a "personal relationship" with Jesus, but an invisible spirit just isn't a substitute for a real flesh-and-blood human being sitting there in front of you.
On the other hand, I can imagine that there have been innumerable cases where this "divine" status has been abused in Hinduism and other religions. When a certain type of person is treated like a god, or as more important than God, then abuse simply cannot be that far behind. Gods in religious mythologies are portrayed as abusing their power all the time, so it would be a shock if human beings didn't do the same.
Christians claim to have a personal relationship with Jesus Christ, but such a relationship can only exist in their minds. Some Hindus, in contrast, may claim to have a personal relationship with a person whose soul is actually "the descent of the divine being to earth" — a person they can see, hear, and touch. Tough competition, huh?
Instead of seeking the divine in human beings, though, why not just look for the humanity in human beings? If you need to see something divine in a person in order to not treat them shamefully, that sends the message that you don't value humanity and don't really want to treat them decently in the first place. Why would a genuinely good person require some abstracted "god" from which all humanity has been stripped to make someone else "good enough" for decent treatment? This is a profoundly anti-human attitude that is being disguised by mediocre consequences.
If someone doesn't like me, doesn't wish me well, and doesn't want to treat me decently, I think I might prefer it if they admitted this openly rather than force themselves to ignore my humanity and focus only on an alleged "divine" spark in me just to make the effort to be civil and decent. This might lead to more rudeness from Christians, but wouldn't it also lead to more honesty from them?
Once the detritus of false smiles is wiped away, perhaps the path will be open for them to treating people well on the basis of their actual humanity — like atheists and humanists have already learned to do.