"Widows, orphans, and strangers", that's code in scripture for the three most vulnerable groups within a society at any given time. And both the great Jewish prophets and Jesus, himself, assure us that ultimately we will be judged by how we treated these while we were alive.
It's interesting to look at any given book in the bible ask this question: "What did the author of this book consider as the very essence of religion? You'll get different answers. For example, if you had asked that question to the authors of Exodus, Deuteronomy, or Numbers, they would have answered that what was central to their faith was proper religious practice, keeping the Commandments and being faithful to the other prescribed codes of religious practice of their time.
However when the great prophets (Isaiah, Jeremiah, Ezekiel, and Joel) came along they painted a different picture. For them, true religiosity was not identified simply with fidelity to religious practice; it was judged rather on how one treated the poor. For them, the quality of your faith is to be judged by the quality of justice in the land; and the quality of justice in the land is always to be judged by how "widows, orphans, and strangers" fare while you are alive. For the prophets, the practice of justice took priority over proper religious belonging and fidelity to religious practice.
We see numerous sayings by the prophets that warn us that what God wants from us is not sacrifice on altars but fair wages for the poor, not the recitation of prescribed prayers but justice for widows, and not the honoring of religious festivals but the giving of hospitality to strangers.
It should be noted, of course, that, after the prophets, we have the great wisdom figures in Jewish history. For them, the essence of religion was neither faithful religious practice nor simple outreach to the poor, but having a wise and compassionate heart, out of which you would then be faithful to both proper religious practice and outreach to the poor.
This is the tradition that Jesus inherits. What does he do with it? He ratifies all three. For Jesus, true religiosity asks for all of these: faithful religious practice, outreach to the poor, and a wise and compassionate heart. For Jesus, you don't pick between these, you do them all. He tells us clearly: "If you love me, you will keep my commandments" (John 14); but he also tells us that we will ultimately be judged on the basis of how we treat the poor (Matthew 25); even as he tells us that what God really wants from us is a wise, compassionate heart. (Luke 6 & 15)
For Jesus, we are true disciples when we have compassionate hearts out of which we keep the commandments, humbly worship our God, but make it a religious priority to reach out to the most vulnerable groups in our society. Indeed, on this latter point, Jesus' warnings are much stronger even than those of the great Jewish prophets. The prophets affirmed that God favors the poor; Jesus affirmed that God is in the poor ("whatsoever you do to the least, you do to me"). How we treat the poor is how we are treating God.
Moreover (and I doubt we've ever taken this seriously) Jesus tells us that, at the final judgment, we will be judged for heaven or hell on the basis of how we treated the poor, particularly on how we treated the most vulnerable among them ("widows, orphans, and strangers"). In Matthew 25, he lays out the criteria upon which we will be judged, for heaven or for hell. Notice that in these particular criteria there aren't any questions about whether we kept the commandments, about whether we went to church or not, or even whether our sexual lives were in order. Here we're to be judged solely on how we treated the poor. It can be rather frightening and confusing to take this at face value, namely, that we will go to heaven or hell solely on the basis of how we treated the poor.
I highlight this because today so many of us, sincere, church-going, Christians do not seem to have either an eye or a heart for the "widows, orphans, and strangers" around us. Who are the most vulnerable groups on our world today? Who today, as Gustavo Gutierrez defines the poor, does not have a right to have rights?
Let me risk stating the obvious: Among the "widows, orphans, and strangers" in our world today are the unborn, the refugees, and the immigrants. Happily, most sincere Christians are not blind to the plight of the unborn. Less happily, too many of us are religiously blind to the plight of millions of refugees looking for someone to welcome them. Every newscast we watch tells us that we're not much welcoming the stranger.
How soon we forget God's warning: "You are to love those who are foreigners, for you yourselves were once foreigners." (Deuteronomy 10, 18-19)