A Therapist’s perspective
A therapist's perspective on the larger context of our growing ideological divide (after all, understanding intense emotion and helping to resolve seemingly intractable interpersonal conflicts arising therefrom, are, so to speak, a psychotherapist's " bread and butter") should provide some guidance in mitigating and resolving it. A good psychological assessment of our increasing ideological divide will first highlight how in the face of anxiety and traumatizing uncertainty, people tend to embrace ideologies and fanaticism in the service of self-cohesion and "terror management" 
From a relational, intersubjective psychoanalytic perspective, our current ideological divide also expresses the defense mechanisms of projection and "negative judgement", narcissistic disconnection from others, and dissociation from affect cloaked by ideological judgements blocking empathy. The proliferation of cognitive distortion (including conspiracy thinking), and of fear and disdain for the "other" - both by partisans of the right and the left - can be understood in this context.
In assessing our current ideological divide, it is helpful to be reminded that everyone (even the researcher and scholar of ideologies) has an ideology. They are the intellectual scaffolding which allow us to construct a satisfactory life, and reflect the myriad biological, environmental, experiential and cultural influences that have shaped us to be who we are.
Where psychology comes in is understanding how something normal and even healthy can become abnormal, excessive and pathological. If a person totally embraces an all-encompassing ideology (e.g. is "in the grip of" a radical political belief system) they tend to lose their humanity. A die hard fanatic leftist and follower of the Communist ideology will subordinate their entire existence to serving the cause. Another way to understand extremist political ideology is that it allows a person to avoid resolving their psychological issues and relieves inner distress by projecting it onto the political realm. A person with a weak or vulnerable sense of self can bolster their weak self-organization by embracing, for example, an ideology that boosts their self-esteem, unfortunately most often at the expense of a despised other group. Racists who might otherwise feel worthless, can with their racist belief system, at least feel superior and proud of their "whiteness", anti-Semites can project onto "the Jews" their own unsavory impulses to cheat or get ahead (See Jean Paul Sartre, Anti-Semite and Jew for a brilliant philosophic-psychological analysis of this.
Psychotherapists, as Albert Ellis and Aaron Beck have taught us, need to stay aware of how people are prone to "cognitive distortions" that are irrational (or a better term, unhelpful for living together with others). Extreme negative conclusions about the future ("catastrophizing"), or the idea that there is a perfect solution to our problems, and lacking it, it is a disaster and we can't move forward, are among some of the most common cognitive distortions and easily can be seen in political expressions today. Extremist ideologies freely engage in distorted thinking and paranoia, as the complexities of social issues and problems are crammed into the rigid categories of the dogma, generating despondency or rage, paralysis or dysfunctional behavior, and even violence.
Psychoanalysis has much to offer here as well. Interpreting why a person clings to or has embraced an extremist ideology can be understood in developmental terms, or as a way of resolving intractable inner conflicts, or the expression of "unconscious organizing principles" which operate automatically, and can be changed when brought to the light of consciousness and critically examined. Projection and "negative judgement" are well known patterns which psychotherapists observe in patients who are in psychological and emotional distress. As the psychoanalyst Nancy McWilliams has pointed out, projection is a process not an essentialist trait, one which nearly everyone is susceptible to when overly-stressed or in a state of regression. Anti-attitudes and the judgements of laziness (vs. productivity), stupidity (vs. intelligence), and otherness (vs. compassion), can each be seen as ways of projecting feared unacceptable self-traits onto others. The rush to judge those whom one categorizes and castigates as the epitome of wrongheadedness (e.g. conservatives who conjure up with derision an entity such as "The Left", (or more radically, the "Libtards"), or liberal leftists who focus on the threat of "the Right" as a monolithic bloc and consider irredeemable and racist those who gravitate toward a conservative viewpoint, illustrate divisiveness and proneness to conflict, as well as disdain for the "political other." The way forward that could bring reconciliation, psychotherapists can point out, will not be grounded in attacking another's ideology so much as understanding and transforming the emotional needs that underlie it.
If there has emerged a "culture of narcissism" as Lasch both described and predicted, then what is needed is not moralistic judgement and psychopathologizing, so much as understanding and interpretation of meanings. Self-absorption and dissociation from connection to others are essentially "dysfunctional" traits, and what is needed are practical and policy efforts to decrease them. Insofar as narcissism excludes empathy and compassion for others, the therapeutic goal is to cultivate connection and to illuminate and break down rigid defenses against dependency and vulnerability.
A therapist's perspective on our current ideological divide can also incorporate the insights of family systems theory and systems and complexity theory in general. Rather than seeing the varied and conflicting cultural positions within our ideological spectrum as distinct and separate, we can recognize their interconnectedness and how they express the larger system in different but interlinked ways.  Left and right define themselves reactively in terms of each other, opposites but mirroring one another and exacerbating differences at the expense of their common identity and belongingness to the same larger community. The therapists task is theto encourage separation-individuation from the oppressiveness of systems and to facilitate breaking out of negative habits of conflict and to forge new patterns of cooperation.
Both psychotherapy and mediation offer hope. Both require the challenge to face one-self on an individual level and both presuppose that if a collaborative engagement rather than avoidance take place between opposing parties, the opportunities to diminish misunderstandings and acrimony can be enhanced to great extent. The next part of this article will address in greater detail how different manifestations of personal and interpersonal dysfunctions contribute to our contemporary ideological divide and how distinct pathologies and sociopathy enhance the severity of conflict. It will also provide an analysis of the ‘rescue mission’ humanity now needs to ponder and embark on, if it wants to resolve the critical issue of coexistence
 This is a founding principle for the field of political psychology. See Harold Lasswell, Psychopathology and Politics (University of Chicago Press, 1930)
 See Kenneth Rasmussen, “Political Polarization in Contemporary America”, Cleo’s Psyche, December, 2012 and Peter Loewenberg, “The Psychology of Racism”, in G.B. Nash & R. Weiss, The Great Fear: Race in the Mind of America (Holt, Reinhart & Winston, New York, 1970).
 Albert Ellis, Overcoming Destructive Beliefs, Feelings, and Behaviors: New Directions for Rational Emotive Behavior Therapy, (Prometheus Books, New York, 2001); Aaron Beck, Cognitive Therapy and the Emotional Disorders, (International Universities Press, Madison, CT, 1975.
 Robert Stolorow, Psychoanalytic Treatment: An Intersubjective Approach, (Hillsdale, NJ, Analytic Press, 1987)
 see www.psychologytoday/com/blog/the-me-in-we/201702/new-insights-paranoia
 Irene Goldenberg &Herbert Goldenberg, Family Therapy: An Overview (Wadsworth/Thompson, Belmont CA, 2000)
 On complexity theory and its uses in psychoanalytic therapy, see William Coburn, Psychoanalytic Complexity: Clinical Attitudes for Therapeutic Change, (Routledge, New York, 2014).
 Using a systems approach, the theorist Murray Bowen emphasized the importance of achieving “differentiation” from (vs. fusion with) others within a family unit. See Bowen, Murray (1974), "Toward the Differentiation of Self in One's Family of origin", Family Therapy in Clinical Practice (reprint ed.), Lanham, MD: Rowman & Littlefield, published 2004).