Mission trips are trips, typically short-term and often international, taken by Christians to share the Gospel with the people visited.
What types of mission trips are there?
Medical mission trips provide medical care and share the Gospel. Construction mission trips engage in building projects and share the Gospel. Sports mission trips engage the locals in sports, and share the Gospel. Musical mission trips perform music, and share the Gospel. Child care mission trips provide childcare, typically in orphanages, and share the Gospel. This list can go on.
What if there is no Gospel-sharing during the mission trips?
Then they are humanitarian - not mission - trips. Mission trips focus on the eternal destiny of the people visited by addressing their need to repent of their sins and believe the True Gospel. Humanitarian trips only address their earthly needs but leave them hell-bound.
What proportion of today's "mission trips" are actually humanitarian trips?
The majority of them. For example, a medical "mission" trip that dispenses thousands of dollars of medicines after spending tens of thousands of dollars on airfare but shrinks from sharing the Gospel for fear of offending the local religion is a costly humanitarian trip that should remember Jesus' warning, "For whoever is ashamed of Me and My words, of him the Son of Man will be ashamed when He comes in His own glory, and in His Father’s, and of the holy angels" (Luke 9:26).
Other "mission trips" are not even humanitarian trips, but sightseeing trips to visit places where non-Christians visit, including idolatrous Roman Catholic cathedrals in Europe or demon-worshipping Buddhist temples in Asia. "Mission trip" has become the label slapped on any trip taken abroad by a group of Christians for which a well-connected travel agency charges a premium and after which the tourists return home as short-term "missionaries" instead of humanitarians or sightseers.
Aren't mission trips stepping stones for some to become missionaries?
If they are to get a taste of missionary work, they need to do what missionaries do: share the Gospel. But before paying money to share the Gospel abroad, they need to have shared the Gospel at home and integrate Gospel sharing into their everyday life, lest they develop the false impression that sharing the Gospel is what you do away from home. Also, their mission trip needs to last not a couple of weeks but several months, long enough for the initial euphoria to subside and for the cultural, linguistic, social and dietary challenges, the loneliness and other realities of the missionary life to be felt.
Don't the local Christians appreciate being visited?
They do, but not without regret. If 10 members of an American church go on a week-long "mission" trip to paint a church building in a poor country, the local Christians appreciate the paint job, but also know that if the money for the 10 international airfares had simply been given to them, they, who may be living on less than $5 per day, could have painted their church building and would have been helped a lot more by the rest of the money.