How do Mormon missionaries learn foreign languages so quickly?

Because the gift of tongues is real and present in the Church of Jesus Christ of Latter-day Saints, and because of the urgency and importance of the Lord's great commission to preach the Gospel to every creature, "to all nations", baptizing in His name.

All else, including study practices, diligence, personal motivation or aptitude, tutoring, metrics, immersion and programs are merely appendages to these facts.

As the Lord promised, this is the kingdom that will never be destroyed: "the God of heaven will set up a kingdom that shall never be destroyed, nor shall the kingdom be left to another people. It shall break in pieces all these kingdoms and bring them to an end, and it shall stand forever," "and fill the whole earth."

In a phrase, because the Lord promised that it would be so. He prepares His missionaries as He said.

I served as an Elder in the LDS church as a missionary. While I didn't serve a foreign mission, my brother and my father (the first in his family to join the church) did.

It's been mentioned several times in responses that in order to understand many of doctrines and principles of the LDS church all stem off of the belief that Joseph Smith was a prophet and that God (Our Father in Heaven) communicates through a prophet today as he has always done.

Contrary to the rest of Christianity, we don't believe the gift of tongues as most other Christians do. My buddy was Presbyterian, and I think has since converted or is in the process of conversation to the LDS church, and many others Christians I've known whom have prayed, speaking in tongues. I even have a life-long buddy that claimed to be pagan or Satanist that claimed he had a moment in which he "spake in tongues".

The fact of the matter is this, by our beliefs as LDS members, the gift of tongues is the ability to understand a spiritual message spoken by the Spirit, in one's native tongue, or the ability to learn a foreign language in order to preach the message among our Father's children. It's not some secret code or babble, it's an Elders ability to rapidly learn Spanish, English, or Mandarin at a rapid pace. In my experience, I served an English speaking mission but, I found I was able to communicate the message I was sent to deliver in a way I'd never been able to communicate with others before. I did it well. That was the gift of tongues, or gift of the spirit. I did learn a little German in school but nothing religious related but knocked on someone's door. They answered and only spoke German, but I was able to instantly convey a very basic simple gospel point in German. I may have been prepared in High School, but that language was quickly brought back, long enough to say my peace and then that was it. Never used it before and not after, that may have been the gift of tongues as well. It's not a secret, it's being open to the Spirit and granted the authority to be called to use that ability by God Our Father, not by a man having no authority. That's the beauty of having a living prophet.

There have been many good answers on this subject. Having been an observer of the missionary process to learn a language, I will share my insight.

They do immerse themselves into the language from day one in their training. As much as possible, they try to avoid their native language and attempt to communicate in the new language as exclusively as they can. This indeed accelerates the learning process.

However, even accelerated, even the military has studied the LDS language training process and has attempted to duplicate it as much as possible. Even they cannot seem to match the success rate from what I have seen, but they try.

When a missionary goes out, they often are not very fluent in the new languages. This makes for some very comical situations when they use a wrong combination of words that suggests something far from what they intended it to mean.

On the spiritual side though, there have been countless witnesses of missionaries who, when fairly new in the language, barely able to speak it well, if at all, have experienced moments when their minds just opened up and marvelous words seemed to flow from their mouths for the duration of a time, stunning not only themselves but those around em.

I believe very firmly that the gift of tongues is given to these missionaries. I believe that anybody who is sincere in their hearts in Jesus Christ can also experience this wonderful gift from time to time. After hearing the witnesses, there is no question in my mind that this gift is manifest in people far more than any of us realize.

I work at the Missionary Training Center and my boss often speaks of when officials from the Army's language school came to study our curriculum to try and figure out how our missionaries learned languages so fast. (Below are links of two people's personal stories confirming this.) One big factor is that they are taught in total immersion from day one and as soon as they learn something new they are expected only say it in the language they are learning. When I was in the MTC we were taught to pray in Spanish on the first day and were expected to only pray in Spanish for the rest of our missions. Anyway, there are some thoughts for you. I hope this helps!

https://dteeps.wordpress.com/2011/08/03/mormons-and-language-learning/

http://www.npr.org/2014/06/07/319805068/lessons-from-the-language-boot-camp-for-mormon-missionaries

My experience was that those missionaries who are required to learn a foreign language usually spend 8-10 weeks in language training. Some missionaries have previous exposure to the language of their mission. The instruction they receive emphasizes religious vocabulary they will use in teaching and is a limited subset of the full language. It is a full-immersion program: after the first two weeks, they are expected to communicate in their mission language only, which provides a motivation for intensive self-study. When they arrive in the field, they are assigned an experienced companion who is already reasonably fluent in the language, or may not even speak English at all. In some missions, they may be asked to spend a half hour or more daily in language study. In the process of teaching, they are engaged nearly full-time in conversation and attempts to converse with native speakers. These factors combine to make the whole process faster and more thorough than the typical college or commercial program. This basic program has been in place for approximately the past 50 years, as outlined in the Missionary Training Center Wikipedia article.

It is understood that the gift of tongues is given more for the purpose of helping missionaries preach and less as a sign to non-believers. Various accounts of missionaries in the 19th and early 20th century report incidents in which missionaries became temporarily fluent in languages they had struggled with. Although missionaries are still encouraged to pray for the gift of tongues, it is more often expected to come in the form of enhancement of the missionaries' own efforts than evident miraculous display.

Reflecting back on my mission experience abroad, I can say that it comes down to three main reasons to answer, "Why do Mormon missionaries learn foreign language so quickly?"

1) The belief in the gift of tongues: If this belief is constructive, like recognizing one's own progress, talents, self-worth, and endors*m*nt/intervention from God without making comparisons to other missionaries or native speakers, it can be very empowering.

2) Persistence in imposing reception: Missionaries gain access to the native speaker community by actively and constantly seeking out the people that value their gospel message. This means a lot of interaction with native speakers to fulfill their mission call.

3) Instant membership in the language community: Missionaries already have enhanced language learning since they are well received by local Mormon native speakers who treat them like family by feeding them lunches and dinners, and see them as oracles when it comes to the Gospel and Church policies. They also have instant and constant membership in their small companionship communities. This may involve a constant companion that speaks the second language. Their is also the missionary community which creates a positive peer pressure that expects them to use the designated morning language study hour and make group goals to speak only the second language in meetings and/or among each other.

Bottom line is that knowing the second language very well is a fundamental part of their identity and purpose. But missionaries do have restrictions; they cannot use media that is not in their approved library; so they and are not too familiar with politics, news, and culture that is in the second language media. They are also very focused on talking about their Gospel message; so their writing ability does not develop as much as their speaking ability.