I and countless other Mormons served missions because we love the gospel plan and want others to be able to follow a good path. We did it for free for 2 years! Mormons are giving, generous members who are there to serve whenever others need them! I haven't seen one church do this besides the Mormons.

We do not doubt in the least that you and other missionaries were/are in the mission field because you love the gospel plan of Mormonism and have a desire to help others achieve happiness in this life and beyond. No one at Equipping Christians Ministries and other ministries like it doubt the sincerity, commitment, and integrity of LDS missionaries. We at E.C. have sons, brothers, relatives, and friends who served honorable missions for the LDS Church. We know they have a strong love for the gospel as taught by the Mormon Church and truly care about people. We know there are giving, generous Mormons. Many ward members financially support young men and women on missions whose families cannot contribute.

It is no surprise that you have not seen one church do this besides Mormons. When we were LDS we were very provincial in our views as well. We did not look for the good among Christians any harder than Al Gore would look for an iceberg or Rosie O’Donnell would look for a husband! Our vision rose and set with the sun of Mormonism and believed that Mormons had the corner of the market on goodness, kindness, generosity, service, high standards, and truth. We really thought that all the modern inventions from radio and television, to vaccines and the space shuttle were invented by Mormons! We were uncertain about the internet, as Al Gore seemed to have some claim on that, but we were sure everything else of value and worth came about because Mormonism was on the earth in these “latter days.”
  
After coming out of the bubble we lived in as Mormons, we were astounded by the selfless acts of service done by millions of Christians from all denominations around the world and the contributions they have made for the benefit of society. Christians give generously of their time and money. Churches across the country are responsible for the establishment of women’s shelters, homeless shelters, adoption agencies, soup kitchens, drug rehabilitation centers, prison ministries, ad infinitum! In the Kansas City area alone, over 6,000 men recently gathered to build pre-fab homes for the poor and needy---without pay! When Hurricane Katrina left thousands of people homeless, there were thousands of Christians who flew in, drove in, and came by busloads to help. We know people from our churches who drove to New Orleans on weekends and even took their personal vacation time to minister to the needs of the people in those devastated areas. These Christians, who came from a variety of denominations, volunteered, freely giving of themselves because of their love for Jesus and love for people. We do not know many LDS who would give up their family vacation to go help non-members.

The Gideon Bible Society is one example of generous service;

The Gideons International started distributing the Word of God in 1908. Today, [they] have more than 290,000 members—and an untold number of supporters—in more than 190 countries across the globe. These dedicated individuals give their time and money to make it possible for others to learn about the love of God by giving them access to His Word. In fact, [they] have placed or distributed more than 1.6 billion Bibles and New Testaments around the world . . . and counting. (http://www.gideons.org/AboutUs/WorldwideImpact.aspx)

Hundreds of thousands of Christians over the last century alone have gone on missions; anywhere from a few days to a few months to a few years, with many committing their whole lives to missionary work. They do not receive pay for this! The teenagers at our church saved up money to go to a small Native American Indian community to help the people repair their dilapidated houses, provide meals, and run a Vacation Bible School program for the children to learn about Jesus. The cost of the mission trip and the money and supplies for the poor and needy came out of the pockets of the teens and other church members gladly and cheerfully. These awesome young men and women worked hard all year to raise much of the money by doing community car washes and other fundraisers. Thousands of Christians of all ages all over the country and tens of thousands all over the world engage in missionary work and service, bringing the gospel of Jesus Christ to the lost. They don't just give a brief message and then cut off communication when a person or family doesn't commit to baptism or joining a church! Instead, they love, serve, and build lasting relationships with the people they minister to. An inexhaustible number of incredible stories exist of angelic protection, miraculous healings, and amazing conversions experienced and witnessed by Christian missionaries! 
  
When LDS it would have made our heads spin to realize all that was going on within the Christian community and that the LDS Church was not the alpha and omega. As Mormons our limited understanding of Christian churches caused us to be very patronizing. On the rare occasion we heard of some small church doing something wonderful in a community we would think, “Oh, how precious,” in the same way an adult might observe a small child trying to sweep the kitchen floor with a broom twice his or her size. Our attitude was like, “Oh, how sweet; some people not belonging to ‘the true church’ are trying to do something nice for society! Well, bless their little heathen hearts!” How pathetic of us. Praise God He delivered us from such obnoxious pride!
  
As previously stated, many Christian missionaries spend their whole lives in service to a group of people, whether that group is a remote tribe in a Third World country or the homeless in an inner city in the States. These faithful Christians are not getting paid for their labor. We encourage you to do some investigation and see for yourself all the good that Christians and Christian churches do across the world. Naturally, you will not hear about the selfless service of Christians within the wards and stakes of the LDS Church. You probably won't read about it in the newspapers either, because the various Christian churches don't hire publicists to put their good works on public display. You see, they are not doing these things for recognition or to promote their denominations. They do it for the glory of God, to honor Him and bring others to a saving knowledge of Jesus Christ.