What’s at play here seems to be the conversion theory of minority influence- that a unified minority with a consistent message can impose its will on the fractured majority. I saw this during the Women’s March on Washington, which seemed to be a potpourri of every liberal cause on display. The Trump movement coalesced and was able to hijack the GOP. Clinton’s weaknesses allowed it to win. But the key to fighting back is creating a new consistent message for a liberal democratic order along the line of the themes David mentions here: unprecedented prosperity; evidence based decision-making; trust; equality. Add in more attention to those left behind by progress and you have a unifying theme. Where the Blue Church goes off the rails is its own non-evidence based orthodoxy (see GMOs, social reengineering, religious faith in government solutions) and its desire to cram orthodoxy down people’s throats.
The Blue Church just needs to create a core of evidence-based truth and focus on that message, while not letting fringe interests hijack the movement.