The real reason is the total abandonment of Judaeo-Christian teaching, with SECULAR thought taking its place
The answer is in this as in so many other areas, the left and the right are working from premises that are more or less polar opposites. Jesus says Love your enemies, and pray for those who persecute you (Matthew 5:44). This has long been interpreted as meaning that one should treat everyone, even ones political opponents, with respect, and have compassion for them when they suffer. This remained a cultural ideal long after many Americans began to discard their Christian faith and is still taken for granted among many people, albeit in the United States increasingly only among conservatives of all faiths.
The real reason is the total abandonment of Judaeo-Christian teachingGodless people always fear the future and death. Plus their belief system is built on sand, and shifting sands create fear (consternation). If a Leftist could stop the hate and rage for just a moment and truly look at themselves, they'd see a dog chasing its tail.