The one inviolable tenet of Mormonism is the idea that the Mormon Church is the "one and only true Church" on Earth. This fact is the driving force behind the aggressive proseletyzing efforts; Mormons believe that the Mormon Church is the only avenue to Heaven. To bolster conversion rates, every young man is expected to serve a two-year proseletyzing mission. The pressure to serve a mission is very intense; the young women of the church are instructed not to date men that haven't served missions.
In addition to full-time missions, members are expected to use their relationships with non-members in order to boost conversion. The idea is that "every member is a missionary" and should be on the look-out to promote the Church. To this effect, my peers and I availed ourselves of every possible opportunity to invite friends to youth activities. Most of the time, our friends would come to the activities but say no to conversion. A few of them were baptized; some remained in the church, others became inactive after a few months. My father was also very vigilant about trying to convert people; sooner or later he would try to give every non-member friend a Book of Mormon. Most of the time, he ended up alienating potential friends with his excessive zeal.
This attitude of members that every person needs to be Mormon is part kindness, part arrogance. Kindness because members want non-members to be happy and think that they need Mormonism to attain happiness. Arrogance because members believe that their way of life is superior to others. At church, I felt uncomfortable by the attitude that non-members were lost and confused. Our entire culture was built around the idea that we were the only people with the truth and that we needed to spread the truth to world at large.
By promoting this idea of "every member a missionary", relationships between members and non-members are fraught with the tension of potential conversion. Some members are able to maintain respectful interfaith relationships. Others aren't.