A very important part of LDS practice is the development and bearing of testimonies. A testimony is a public statement of faith and belief. Because having a testimony is considered to be an important, if not essential, part of conversion, the LDS have developed a very nuance way of talking about the matter. I think there is a lot of confusion about what you must believe in order to have a testimony of the Church, and to believe the Church is true.
In an effort to clear up some of the confusion I propose that for a person to “have a testimony” of the Church is merely to believe that it is God’s will that the person belong and participate in the Church for the good of the Church, its members, and the world.
I like this definition because it allows the freedom of religious belief that Joseph Smith, and many other Latter-Day Saints died for. It also allows for those who have such a testimony openly accept new (or old) teachings without casting doubt on their loyalty to the cause of Zion that the Church has always stood for. If Joseph Smith stood for anything in his life, it was the freedom to proclaim and embrace the words God gave him, whether God gave him those words through experience, ancient scripture, or direct revelation.
I think it is a disservice to his memory and legacy to question somebody’s testimony of the church merely because they embrace radically different doctrine. It is the ability to embrace any and all bodies of truth, which are filled with both wheat and tares, that only sure path for the members to make the Church the true church that they claim it to be.