This dramatic change was summed up at a small gathering of academics and missions professionals at Fuller Theological Seminary in late May. "At (1910) Edinburgh, people thought they were going to take over the world," said C. Douglas McConnell, dean of Fuller's School of Intercultural Studies in his opening remarks. "And now many of our students wonder if they should even try."

Indeed, colonialism is dead (thankfully). But the term "missions" itself now carries with it a negative connotation, even in politically and theologically conservative circles. Christians today typically travel abroad to serve others, but not necessarily to spread the gospel.

While meaning well and certainly doing good, this form of outreach has allowed the pendulum to swing too far from 1910. Today, Christian missionaries need to balance both actions and words. The overwhelming majority of American missionaries today are "vacationaries." Joining mission trips of two weeks or less, they serve in locales where Christianity already predominates.

The purpose, then, of their visit is to battle the ills of poverty and to stretch their own spirituality. According to studies by Robert J. Priest, a missiologist and director of the doctoral program in intercultural studies at Trinity Evangelical Divinity School, 82% of short-term missions today go to countries in the most-Christian third of the world. Only 2% land in the Middle East.

The work these missionaries do reflects a paradigm shift-from spreading Christianity, to living it, says David A. Livermore, executive director of the Global Learning Center at Cornerstone University. "In a postmodern context it goes against the grain to go in and do hard-core proselytizing. To millenials, it really feels like al Qaeda in Christian wineskins." And "that's a good shift," he adds, because "it's caused us to see it's not enough to say Jesus loves you and then jump on a plane and go home."

This is especially apparent in the surge of American Christians now working for African orphanages or fighting the child-sex trade in Thailand. Although no hard numbers are available, missions experts note rising interest in strictly social justice and humanitarian work, even on short-term visits.

Scott Moreau, a missions professor at Wheaton College, estimates that two decades ago half of his graduate students believed building churches abroad was their top priority. "Today, it might be 10%," Moreau says. "Fighting trafficking, orphanage work, HIV-AIDS, poverty-that is probably 50%." (Those remaining have a variety of primary interests.)

In part, that is what Africa needs. The Pew Forum on Religion & Public Life reported in April that neither Christianity nor Islam had much opportunity for further growth in sub-Saharan Africa. At least 90% of people in the 19 countries surveyed identified themselves as Christian or Muslim, so the pool of potential converts outside those religions remains small.

Among the organizations working for social justice in Africa is Invisible Children, a San Diego-based group raising awareness about abducted children, most notoriously those dragooned into warring militias. Invisible Children's media kit emphatically states that its founders "believe in Christ, but do NOT want to limit themselves in any way."

Their motivation, though, certainly comes from a Christian place. "If you take that message-love another as yourself-and you apply that to kids in northern Uganda who are getting abducted, what does that mean? I knew, from that, that I had to do something," says Ben Keesey, the CEO.

Spreading Christianity through deeds alone aligns with a quote attributed to St. Francis of Assisi: "Preach the Gospel always, and if necessary, use words." But research suggests that non-Christians often miss the message without the words.

A 2006 study by Calvin College's Kurt Ver Beek found "little or no difference" in the spiritual response between two groups of Hondurans-one which had its homes rebuilt by missionaries who did not proselytize and the other by local NGOs. Intuition would suggest as much. Unless foreigners explain that they are motivated to help by their religious beliefs, locals may be grateful for the new home but they should not be expected to connect dots that they may not even know exist.

The reality is the Church should be doing both: serving the needy and spreading the gospel. This is what makes the humanitarian work of Christians different than that of the American Red Cross. Both are motivated by the desire to help others, but Christians are spurred by that Jesus thing.

The Rev. Albert B. Collver, an executive with the Lutheran Church-Missouri Synod's World Relief and Human Care division, sums it up well: "It is the recognition that Christ died, that he wants everyone to be saved and that his love for the church is a love for all of mankind."

----Mr. Greenberg is the creator of TheGodBlog.org.