Say "Tim Tebow" and Americans imagine a quarterback, kneeling with his head bowed and eyes closed.

For millions this image is inspiring. For others it's a ridiculous joke.

Say "Colin Kaepernick" and Americans imagine another quarterback, kneeling with head bowed or with his determined eyes gazing straight ahead.

For millions this image is inspiring. For others it's infuriating.

"They're both Christian football players, and they're both known for kneeling on the field, although for very different reasons," wrote Michael Frost, an evangelism professor at Morling College, a Baptist school in Sydney, Australia.

"One grew up the son of Baptist missionaries to the Philippines. The other was baptized Methodist, confirmed Lutheran and attended a Baptist church during college. Both have made a public display of their faith. … This is the tale of two Christian sports personalities, one of whom is the darling of the American church while the other is reviled."

According to Frost, these men symbolize two approaches to faith that some believers think cannot be reconciled. When his weblog essay was picked up by The Washington Post the headline proclaimed: "Colin Kaepernick vs. Tim Tebow: A tale of two Christians on their knees."

Around the world, Frost added, Tebow and Kaepernick represent a church "separating into two versions, one that values personal piety, gentleness, respect for cultural mores and an emphasis on moral issues like abortion and homosexuality, and another that values social justice, community development, racial reconciliation and political activism.

"One version is kneeling in private prayer. The other is kneeling in public protest. ... One preaches a gospel of personal salvation. The other preaches a gospel of political and social transformation."

The problem is that these approaches are not in conflict, according to 2,000 years of Christian doctrine. Frost's bottom line: "The bifurcation of contemporary Christianity into two distinct branches is leaving the church all the poorer, with each side needing to be enriched by the biblical vision of the other."

Kaepernick has, of course, become a national figure with his pre-game protests supporting Black Lives Matter and other efforts to oppose police violence. His comments about faith have, to say the least, received less attention.

"My faith is the basis from where my game comes from," he told a Nevada newspaper before Super Bowl XLVII. "I think God guides me through every day and helps me take the right steps. … When I step on the field, I always say a prayer, say I am thankful to be able to wake up that morning and go out there and try to glorify the Lord with what I do on the field. I think if you go out and try to do that, no matter what you do on the field, you can be happy about what you did."

In his essay, Frost also stressed Kaepernick's work in philanthropy, from support for clean-water projects in impoverished Somalia to his donations to Meals on Wheels.

Tebow, meanwhile, grew up helping "his dad's orphanage and missionary work" before bursting into public life as a Heisman Trophy winner with John 3:16 and other Bible verses displayed on his eye-black patches, noted Frost. Tebow has "been outspoken about his pro-life stance, and his commitment to abstinence from sex before marriage. ... He has preached in churches, prisons, schools, youth groups and a welter of evangelical conferences."

However, the pre-fame Tebow was active in prison work and other social causes and, these days, his Tim Tebow Foundation backs numerous projects linked to medical care for the poor, aid for orphans worldwide and work with special-needs children, especially those with Down Syndrome.

So, is it possible to kneel while praying for body and soul?

This is an old debate. However, the Rev. Billy Graham made his views clear in a pivotal 1974 address at the first International Congress on World Evangelization in Lausanne.

"Our witness must be by both word and deed. You cannot separate the two. Our lives, both individually and collectively, must reflect clearly the truths we proclaim. Faith without works is dead," said Graham.

"The source of salvation is grace. … The means of our salvation is faith. The evidence of salvation is works. … We must squarely face the challenges of our own age. We must be sensitive to human need wherever it is found."