I've heard several times now from people that the Church of Jesus Christ of Latter-day Saints lied to them. They were not told that Joseph Smith married - and propositioned to marry - women who were already married themselves. They were not told that there are certain similarities - some of them stark - between the rituals of Freemasonry and the rituals of the LDS Temple Endowment. They were not told that Brigham Young wrote racist things. They all - to the last person - found these things out and felt duped and have since decided the Church was deceitful.
To be fair, I understand the frustration of their position. No one wants to be duped. No one wants to believe in a system of beliefs that aren't logical or rational.
At times, though, I've wanted to have experiences that made me able to relate in a positive way to those who have left the Church because of anger over being lied to. Frankly, I'm not sure how to respond to the claim that they were lied to. Certainly they feel deceived, I'm not going to deny them the right to feel the way they feel. But I keep coming back to the hope that if I can relate to them, and say "I went through the same thing and this is how I kept my testimony" then hopefully they can follow my example and keep their testimony alive as well.
But it's not on my shoulders to save these people. As a personality trait of mine, I have a hard time hearing the criticisms that are leveled against the Church without feeling defensive (negative connotation implied) and trying to defend the Church - with varying degrees of success (mostly "un-.")
It pains me when they're right. Why can't I go and look at the papryii? Why do Egyptologists say that Joseph Smith got the Book of Abraham wrong? Why did Brigham Young write those awful things? Why did Joseph Smith marry women who were already married?
I'm aware of the answers that are there. Some satisfy the curiosity and some do not. I do not believe the Church has lied to me. I think the Church has done its best to teach me faith in Christ, repentance, baptism, the gift of the Holy Ghost, and how to endow myself with power from on high to endure to the end. On the more embarrassing or 'sticky' parts of history and belief it has been silent-- never forbidding me to explore and to learn, nor encouraging me.
In short, I believe that as long as your heart is soft, the Lord will keep revealing more and more until you understand everything in full. Having the answers that will quell any concern for someone else is impossible; they must seek that light on their own.