Nearly two years after the United States Supreme Court legalized gay marriage, a record 64 percent of U.S. adults support same-sex unions, according to a new Gallup poll.

This represents the highest level of support for gay marriage to date and a dramatic increase since Gallup first started polling on the issue two decades ago. In 1997, just 27 percent of respondents said same-sex marriage should be legal.

For the first time, more than half of those identifying as Protestant Christians (55 percent) said they support same-sex marriage.

There are sharp divisions along political lines. However, Gallup reports that gay marriage is steadily gaining acceptance across the board. More than 70 percent of Democrats and independents support gay marriage, compared to 47 percent of Republicans. In 2011, 69 percent of Democrats, 59 percent of independents, and 28 percent of Republicans said same-sex marriage should be legal.

Aside from the marriage question, 72 percent of all respondents said gay relations should be legal.

Americans are not as supportive of transgender people using the restrooms of their choice, an issue that has made headlines in recent years. In a separate Gallup poll, 50 percent of U.S. adults favored requiring transgender individuals to use restroom facilities corresponding to their birth gender. Forty percent favored allowing them to use the bathroom corresponding to their gender identity.

This sea-change of opinion presents interesting challenges to American Christians who continue to affirm the biblical prohibition of homosexual behavior. For insights about how to navigate these challenges, check out our Influence Podcasts with Joe Dallas, "Discussing Homosexuality with Kindness and Conviction," and with Tim Muehlhoff, "Winsome Persuasion."