Most atheists, these days in particular with new atheism, have little of substance to say. Their arguments are exceptionally poor. They do things like, quote 'problematic' biblical passages that someone else found to show that God has ordered people killed, that sort of thing. They make naive comparisons between belief in God and belief in Santa. They will complain about the crusades and witch hunts. They will scatter a bunch of these half baked notions at you, without stopping to digest any possible response, and walk away feeling triumphant that their 'reason' has triumphed against your faith. These people are problematic only insofar as they can take in others who are very poorly prepared, poorly educated in their faith, and make it sound like educated, smart people need to be atheists. I can't imagine they are a problem for anyone who is rooted. I'm sure there's plenty to say about the run of the mill new atheist, the one who maybe read a Sam Harris book and spent some time snickering on the internet. My concern is more that these types will cause complacency for believers. What happens when a believer encounters of a few of these guys, and then assumes this is as good as it gets from the unbelieving secular crowd as a challenge?
My concern is about those atheists/agnostics who are not a part of this naive new atheist crowd, and have taken the time to get to know their arguments. For those who don't have experience with them, they might be taken as the easier sort I described above. Believers who have only really experienced the easier sort will not be prepared for the sophisticated version of atheist. As one example, there are secular types who are university scholars in the New Testament. It does not seem wise to me to assume that in an encounter with someone like this, I could defeat them no problem. There are secular types who are professional philosophers, and so forth. I'm not arguing that these people are unbeatable, not at all, but it's going to take some real time and effort to deal with what they have to say. The types of atheists who take the time to get to know serious arguments, serious content, are going to pose a risk. It's not because they are right, but it's because naive believers who may have never encountered a real, seriously thought out alternative to their faith will encounter it. These nonbelievers are often a part of an intellectual elite, where the message "smart people are nonbelievers" actually comes alive rather than blithely asserted. They present a worldview that becomes attractive in very subtle ways.
When the truth is that even your most basic Sam Harris and Richard Dawkins type argument can sway some believers to walk away (even if it's only for a time), it seems wise to have a bit more respect for the opposition here. The upshot of what I am saying is, I think believers should not assume every secular nonbelieving type is going to offer easy to dismiss arguments, and that I think believers should be aware of that and overall much more prepared.
My question to you is, what your experiences are with this, if you think I'm correct, and what you'd suggest others do specifically if they want to atheist or agnostics?