The number of Buddhists, Hindus and religiously undefined members of Congress is growing today, as the 115th Congress is sworn in. But while the number of religions represented is growing, the overall dominance of Christians remains virtually unchanged — as it has for decades.

Today, Christians remain nearly 91 percent of Congress, despite being just 71 percent of the population. Their share of Congress is down from 92 percent the last two years, but it's pretty much the same as it has been since the late 1970s, according to data tracked by the Pew Research Center.

What's perhaps most notable about the religions of the incoming class is the growth among Buddhists and Hindus, with three members in each of those categories. Just a decade ago, Congress had never had a Buddhist, and just four years ago, it was swearing in its first Hindu member.

The number of Hindus in Congress is actually tripling today, with Indian American freshmen Reps. Raja Krishnamoorthi (D-Ill.) and Ro Khanna (D-Calif.) being sworn in. They join the first Hindu, Rep. Tulsi Gabbard (D-Hawaii.) As for Buddhists, Rep. Colleen W. Hanabusa (D-Hawaii) returns to Congress to join Sen. Mazie Hirono (D-Hawaii) and Rep. Hank Johnson (D-Ga.).

Both religions now represent about 0.5 percent of Congress — catching up to their 0.7 percent shares of the broader population.

But as they and the ranks of religiously undefined members (now numbering 10) have grown, they haven't really displaced Christians. Rather, they've risen mostly in place of Jewish members, whose ranks have declined from as many as 45 members in 2009 and 2010 to just 30 today.

It bears noting that basically all of this is happening on the Democratic side of the ledger. Republicans remain almost a unanimously Christian party in Congress; they just elected their second Jewish member in Rep. David Kustoff (R-Tenn.) (who joins New York's Lee Zeldin), but their other 291 members are all Christians. So Democrats of an increasing number of faiths have essentially replaced a chunk of Jewish Democrats.

As for the number of Christians in Congress, back in 1979 and 1980 there were 486 of them. Today, there are 485.