Firstly, I am now the proud father of three young sons. My oldest, currently in kindergarten, has a very sharp and inquisitive mind. I believe he has inherited the high intelligence that I, and my father, and my father's father have had. He has already asked us of the veracity of Santa Claus, the Tooth Fairy, and God. My wife and I have lied to him and told him that all are true.
There are, of course, various reasons why we adults lie to children. In the case of my own, they are very young, and I don't want to turn them into broken cynics. Even though there is no God, I think a belief in God is useful for turning children into good, decent adults. My own belief in God as a youth was very helpful for my moral and spiritual development. I think that my son will have no problem finding the truth out for himself when he becomes a young man, and he will be better off for having discovered it by himself.
"When I was a child, I spake as a child, I understood as a child, I thought as a child: but when I became a man, I put away childish things."
As for my other two sons, they are too young to understand or question God.
My wife is starting to come around. I have shared with her most of my doubts, but I have done so as gently as possible. She is currently reading The God Delusion, by Richard Dawkins, which I gave to her for Christmas. She understands and agrees with most of the points Mr. Dawkins has made, but she cannot let go of her belief in God. We talk about the topic often. Her position, if I understand it correctly, is that she needs to believe in God so that she can feel in control of the uncontrollable. Her primary fear is that the children will die young, and she believes that if she lives righteously and prays to Heavenly Father, He will spare them.
As for myself, my doubts have not assuaged over the last three years. Rather, as these ideas have stewed in my brain, my convictions have evolved from gnostic theism to agnostic theism, then onward to agnostic atheism, and at the present I can say confidently that the chance of God existing, and of existing in the particular way I once believed Him to, is infinitesimal. I am effectively a strong atheist, and I live my life with the implicit assumption that there is no God.
I should mention, at this point, that I and my family are still very much active Mormons. We go to church faithfully, we pay a full tithing, we hold temple recommends, we take the sacrament, my wife and I serve in callings, we hold family home evening most Mondays, we read from the Book of Mormon every night, we strictly obey the Word of Wisdom, and we pray together often. We have kept our doubts to ourselves as much as possible.
In short, my wife and I are orthoprax, but heterodox. This may seem contradictory, but even though I no longer believe in God, I do believe in righteousness. In fact, since discarding my belief in God and Joseph Smith's prophetic calling, I have had to discard little else. Most of the gospel principles, with the sole exception of those geared towards obedience to priests, work out just fine with or without divinity. Besides, I think it's advantageous to keep active.
The primary advantage of staying in the church is for the women. My three sons will grow up and marry someday, and I want them to marry the best women possible, which I define as descended-from-the-pioneers-white, upper-middle-class, active Mormons, like us. In other words, I want them to marry attractive, establishment women. Due to the principle of assortative mating, my sons will therefore need to be attractive, establishment men.
I don't want to do anything to jeopardize my sons' eligibility with those attractive Mormon women, and becoming inactive would do that. There will be plenty of time for them to cast off false truths and superstition as they mature in adulthood; there is no need to require them to confront it during the headstrong, zealous age of late adolescence and early adulthood. Let them have a testimony, and let them use it to attract the right kind of women.
Mormonism, for me, is an important ethnic identity which I want my children to share. I hope that they will be thoughtful enough to disregard the untrue portions of our religion as I have, but even if they don't, I expect them to live happy, virtuous lives. They could certainly do worse than to remain true-believing Mormons.