Ancient Jew presented civilization with a radical cultural insight about strangers: they were to be welcomed. That was not a common sentiment in antiquity or in tribal cultures elsewhere up to the present. Strangers were suspect. They were considered threat first and often not given a chance to be proven otherwise. Strangers were killed.
Jews held a strikingly different view. Along with a mandate to care for widows and orphans who were without standing once the man was gone, Jews treated strangers with hospitality because they just might be a messenger from God, in other words, just might be an angel.
And sometimes the strangers were.
Christians inherited the idea and the basic belief that the One God loved all creation - strangers included - without reservation. Slaves, women, children sinners of every kind were found worthy of God's love and by extension, worthy of another person's hospitality.
It was a radical idea 3,000 years ago. And it's just as radical now. Hospitality was not an easy practice then and it hasn't gotten any easier, yet the civic behavior we take as "nice" is rooted in the faith of our fathers and mothers from half a world away.
It takes daily effort to practice that faith. The task is made more challenging because some strangers are such a mess. Yet, if we are faithful to our call, every day we welcome a stranger, we welcome the One God who calls all creation good.