The most recent voting data we have from a general election is from the 2018 midterms in which the Democrats regained control of the House of Representatives, and the Republicans were able to expand their majority in the Senate. Midterm elections are not always entirely reflective of the voting values of the entire country because the voter turnout is significantly lower than presidential elections, which already have considerably low turnout to begin with when considering the millions of registered voters who simply choose not to vote. However, the voting trends among religious groups tend to remain the same over time with little fluctuations. 

In 2018, those who describe themselves as Evangelical Christians backed Republican candidates by a margin of 75 to 22 percentage points. Protestant Christians overall backed Republican candidates by a slimmer margin at 56 to 42. 

The Democrats won the Catholic vote by an even slimmer margin at 50 to 49 percentage points, which is fairly consistent with how Catholics have voted in the past. President Obama won the Catholic vote in 2008 and 2012, with Al Gore and John Kerry winning their share of the electorate in 2000 and 2004 respectively. 

The Democratic support increases even more with voters identifying as Jewish and “other faiths.” In 2018, Jewish voters backed Democratic candidates by a margin of 79 to 17. The “other faiths” category, which would mainly include Islamic, Hindu, and Buddhist voters backed Democrats 73 to 25. 

Then comes the category “religiously unaffiliated,” which Democrats expectedly won 70 to 28 in 2018. This group represented 17 percent of the electorate that year, which has increased each of the past few election cycles. 

When looking at data from voters who say they attend a religious service at least once per week, they supported Republican candidates by an 18-point margin over Democrats. On the flip side, Democrats won 68 percent of voters who never attend.

When looking ahead at how different religious groups will cast their votes in the presidential election between Trump and Biden, it is fair to assume that these voting trends stay somewhat similar. Trump did very well among Evangelicals in 2016, and they were an important factor in his victory as their turnout was the highest it had ever been in a presidential election. Many Trump supporters were worried that his Evangelical support might not have been as high as it was because of all of the moral and character issues that Trump has as a twice-divorced casino owner who has openly had extramarital affairs. 

However, the Supreme Court became a major issue with the open seat needing to be filled, and Evangelicals wanted to ensure that the newest justice would be pro-life. Trump eventually got two picks appointed to the Supreme Court to replace both Antonin Scalia and Anthony Kennedy. 

In the 2020 presidential election, the Supreme Court may be a motivating factor yet again for Evangelicals to vote for Trump in record numbers with the declining health of Justice Ginsburg.