Years ago, my wife and I were planning on adopting (long story) a child. As part of the adoption process, there were some classes that we had to take. Most of them were pretty useful for just about anybody. In one of the classes, we had a lot of discussions, and we talked about grieving and how we deal with it. Different groups had different subtopics, and then they would share what they came up with to the rest of the class. One of the groups had the subtopic of faith and how grieving affects it.
When it came to their turn to talk about it, one lady talked about how people will stop believing in God because of the pain in their life, as they will tend to blame God. I wish that I remember her exact words, because that on its own doesn't really bother me. However, I had to speak up because the discussion basically started to turn into how that could be the only reason why people don't believe in God. (I do remember that this woman's children all had Old Testament names - Noah being one that I remember specifically.)
So, I just had to be me and I raised my hand to contribute. I didn't attack anybody's beliefs, but I pointed out that there are plenty of people who don't believe in God whose reasons have nothing to do with being upset at Him. I even specifically told them that my disbelief had nothing to do with some sort of trauma that happened to me.
And right after I said that, in an epic event of an absolute failure to listen, another woman muttered, "Something must have happened to him." So, even though I specifically said that nothing traumatic happened, something MUST have happened. It's not like I could have, you know, reasons for not believing. I must have been beaten by a priest, punched by a nun, or stabbed by every member of the Mormon Tabernacle Choir.
Anybody who's paying attention to what's going on with religion in the United States (and this is even more true for Western Europe) knows that the current generation is getting less and less religious. Young people are abandoning the faith left and right, especially those who go off to college. While it's possible that things might turn around, as history shows that there have been moments of religious influence waxing and waning, I don't think that we're going to see much of a reversal on this.
In other words, if you're a believer, chances are good that you're going to meet a nonbeliever. It even stands to reason that a friend of yours might lose his or her faith. And probably more likely than it has been for generations, it's quite possible that GASP! one of your relatives, perhaps even a son or daughter, isn't going to believe what you believe any more.
Different people will handle this in a variety of ways. One of my Facebook friends told me that it would grieve her heart if her son ever became atheist. I was going to comment, but I left it alone. After all, if she really believes in Christianity, then how could it not? I guess this is where any nonbeliever who is reading this and is thinking of coming out to his or her family needs to realize that it's probably going to be a big deal. Hopefully you'll be fortunate enough for your family to still love and accept you though.
Anyway, you can find all sorts of articles online from Christians who are writing about why so many young people are leaving the faith. Some are better written than others, but every one that I've seen seems to miss out on something important. An example of this is "Listening to Young Atheists: Lessons for a Stronger Christianity" that was published on The Atlantic's website. When I read it, I found myself pretty frustrated. While I obviously cannot speak for all atheists - and at my age, I'd be fooling myself to say that I qualify as a "young" atheist - I found the article to be frustrating. I really didn't feel like the author was paying attention to what these people were probably actually saying. I'd go more in-depth, but The Atlantic published a response to its own article that hits the mark: "Really Listening to Atheists: Taking Nonbelief Seriously".
If you're a believer and somebody close to you tells you that he or she is no longer able to believe, my advice to you is to do the following: listen to what he or she is ACTUALLY saying. Let's say for the sake of argument that you're right, and your particular belief system is the absolute truth. You're not going to get anywhere if you think you already know why they don't believe as you. If, for instance, they tell you that they don't believe that The Bible is true, do you know what's really not going to help? A Bible quote.
I'm not saying that you have to agree with them. I'm not saying that you have to completely change your world view. I would, however, say that if you're really interested in the truth (as opposed to "The Truth") then at the very least you'll consider that maybe the other person is right. But even with that aside, if they tell you that they don't believe for reason X, and you try and convince them that reason Y isn't a good reason, you're only going to annoy and possibly even alienate them.
I said at the top of this post that this message could be applied to anybody. I know that sometimes we atheists can seem a bit smug, but it wouldn't hurt us to listen to believers. Sometimes believers surprise me with their answers, and while it doesn't change the way I feel, those believers become less of a caricature in my mind and more of a complete human being. I even think that this could be applied outside of the area of religious belief - as sometimes people switch their political allegiances as well. Are you going to assume that your son became liberal because he was indoctrinated by college professors? Are you going to figure that your daughter became a Tea Party activist because she watches Fox News? Those very well might be the reasons, but it's probably better to listen to them tell you that than it is to just assume anything.