He didn't. Ever. His regular habit with religious traditions other than his own was gentle and thoughtful engagement. All of his words of rebuke or challenge were reserved for established and privileged traditions within Judaism itself. Later New Testament authors like Paul continued this pattern.
So in our day, if Christians organize protests against other religions, or in other more subtle ways engage in xenophobic speech or bullying practices, rest assured, they aren't doing it in order to walk in the way of Jesus.
They're doing it for one simple reason. They're afraid for the loss of their cultural dominance. Their fear arises out of what is often called "nativism." Folks with this perspective probably prefer to be call patriots. Either way, inasmuch as they think it is connected to Christianity, and even ultimately the core tenets of our nation's system of values, they are sorely mistaken.
Remember that people don't fear change; they fear loss. Anti-Muslim hate speech, anti-immigrant sentiments against Roman Catholics, all of these arise out of the fear nativists have of the loss of their power.
But when he encouraged self-denial and reversal of power, he really meant it. Then he lived it. Though equal with God, he did not exploit it, and instead took the form of a slave, found in human form, and died the death of one whose life was bound up in giving life to others.
All of this matters for how we engage our Muslim neighbors. Of course it matters for how we engage any religious Other, but I name Muslims because it seems to be the case that bigotry against Muslims is the most socially acceptable form of nativism today.
What are the steps to overcoming this kind of bigotry in our communities, and in our own lives. Well, for one I think a good syllabus can help. We have thoughtful writers who can help us on the journey. Some of my favorites include:
Todd Green, in a recent book on Islamophobia.
Miroslav Volf, in perhaps the most compelling argument from a Christian theologian on the shared faith of our two religious traditions.
An amazing first step in ecumenical dialogue between these two great religious traditions.
For Christians looking for a Muslim perspective on Christianity.
I also tend to think we need to become much more clear on how our "Christianity" has become entangled in idolatrous ways with our nationalism. AKM Adam, in Looking Through a Glass Bible: Post-Disclipinary Interpretations from the Glasgow School, writes:
If we take Sacramerica seriously as a signifying practice of veneration of national identity, as a social system, we can see a sort of performative mise-en-abîme when politicians make a great show of their determination to display the Ten Commandments as integral parts of civil business. The central figure in the Ten Commandments controversies has been Roy Moore, a judge, politician, and columnist from Alabama. Moore repeatedly insisted on the prerogative of displaying wooden plaques bearing the Commandments in his courtroom, beginning from his appointment as a circuit court judge in 1992. Once he was elected Chief Justice of Alabama—arguably on the strength of his pro-God, pro-Commandments stance against the American Civil Liberties Union—Moore commissioned and installed into the Supreme Court building a granite monument crowned by two tablets bearing an English translation of the Ten Commandments. In so doing, he defied prevailing interpretation of the establishment clause of the Constitution (specifically the ‘Lemon test’) and, eventually in 2002, the legal judgment of the U.S. District Court.
But while Moore repudiated the authority of any courts that did not acknowledge the God of the Commandments as the source of their authority, he exemplified the signifying practice of Sacramerica. His integration of a pastiche of biblical and theological claims with the civil identity promulgated in the Constitution and selected quotations from canonical founding politicians captures both the feverish ardour of Sacramerican piety and the paradoxical affirmation of idolatry expressed when one of Moore’s supporters decried the removal of the Ten Commandments monument by shouting ‘Get your hands off our God, God haters!’ That supporter articulated the Sacramerican conviction that the love of God entails the love of the United States, made physically available in the form of a stone monument—a monumental stone tablet—on which are inscribed (in English) the very Commandments that forbid worship of, or construction of a sculpted representation of, any rival God.For more on the historical origins of our strange religious nationalism, which is in Christian tradition, actually a heresy, the heresy of phyletism.