Adam Geller, President of National Research, addresses Monmouth County Republicans.

As a practitioner of public opinion polling, I’ve studied, poked and analyzed opinions for more than 25 years. I’ve learned and grown to appreciate how fickle and malleable opinions can be. I’ve also come to understand through opinion research, why President Trump is playing a winning hand going into 2020 and why he is better positioned for victory than you might think.

Mr. Trump isn’t playing the opinion game. He is playing on a different field. He is playing on beliefs and values. And his opponents are all too happy to assist him.

Opinions can change, and they often do. Beliefs don’t change. We can change our opinion about a candidate, or a restaurant, or a TV series. But we don’t change our fundamental values. We don’t change our beliefs. Opinions are ephemeral. Beliefs are unwavering.

Many of us believe in God. It’s not an opinion. It’s a belief. Our nation was founded on Judeo-Christian values, not Judeo-Christian opinions.

Mr. Trump understands this distinction, and is riding this straight to a victory party on Nov. 3, 2020. In fact, the contrast between Mr. Trump and the Democratic field is a demonstration of just how much Mr. Trump understands the American psyche and just how much most Democrats do not.

Look no further than the midsummer Democratic debates and the concepts that the Democrats are pushing. Open borders. No more private insurance. The elimination of the Electoral College. Packing the U.S. Supreme Court with liberal justices. Abortion rights for transgendered men (!). A war on Betsy Ross and our nation’s Founders. Free health care for illegal immigrants.

These aren’t a series of individual issues. They are an attack on the fabric of America and American institutions and sovereignty. They are an attack on American culture. They are an attack on the belief of what America is; what America represents. The American ideal that most of us over the age of 30 grew up with.

Voters don’t process these as opinion issues or thought experiments. They process them as value propositions. They process them as challenges to their fundamental belief systems. That’s why public polling shows deep opposition to these proposals among the very swing voters Democrats are hoping to attract.

In fact, surveys like July’s NPR/PBS NewsHour/Marist survey are, at this point, more instructive than the traditional approval and horse-race polls that populate our inboxes and airwaves. The NPR polling showed the vast differences in support between Democrats and independent voters on some of the key policies that the Democratic presidential candidates are running on.

For example, while 60 percent of Democrats support a national health insurance program for immigrants who are in the U.S. illegally, only 27 percent of independents support it. Sixty-three percent of Democrats support abolishing the Electoral College, while support among independents is only 44 percent. Sixty-four percent of Democrats support “Medicare for All” — but only 39 percent of independents do.

In the August 2019 WSJ/NBC national survey, much attention was paid to the “generational gap” that exists on the importance of American values, such as patriotism, religion and having children. According to the Aug. 25 Wall Street Journal, views on these traditional American values varied by age.

But a closer read of the data suggests deep fissures within the Democratic Party. From the Journal: “Generational differences on personal values were most pronounced among Democrats. In fact, the views of Democrats over age 50 were more in line with those of younger Republicans than with younger members of their own party.”

The reckoning that Democrats will face is this: The proposals driving their energized, progressive, younger base, when deconstructed, is an assault on the American fundamental beliefs in capitalism, autonomy and electoral representation.

That is also one of the reasons why Mr. Trump’s “Capitol 4th Celebration” last July was such a politically astute move. Despite the Democratic protests (“it will be all about HIM!”) it was the perfect contrast to what voters were hearing from the left. It was a nostalgic and not-so-subtle reminder of many of the cultural touchstones that are embedded in our DNA. It was Mr. Trump reminding us that it’s OK to be proud. It’s good to be an American. It’s good to be a patriot. It is OK to be filled with American pride on the most American of holidays. These aren’t opinions. These are beliefs.

While horse-race polls have their place, my own polling as one of the Trump pollsters in the 2016 presidential campaign, replicated elsewhere, show that reluctant or hidden Trump supporters are still very much part of the polling landscape and will continue to be part of the story as this president is attacked daily by the media and Hollywood elite, and his supporters are physically and verbally assaulted by an increasingly violent and militant left. Some respondents would rather not tell a stranger on the phone or Internet that they support Mr. Trump, fearing potential consequences or backlash. Ignore them at your own peril.

The 2020 race is shaping up thematically. At its most bare deconstruction it is this: We can either preserve American institutions, and the value proposition that Americanism represents, or we can tear it down. Regardless of voters’ opinions on Mr. Trump, they will vote their fundamental beliefs. And Donald Trump will be re-elected.

Adam Geller, a public opinion researcher who worked on the Trump-Pence 2016 campaign, is a pollster for America First Action SuperPac.  He lives in Monmouth County, NJ