I am atheist, solid and sure, but I can't describe myself as a humanist because I don't like humans very much. I'm rather comforted by the idea that I won't know or perceive anything when I die, it'll be like when I wasn't born yet.
I completely agree with the previous posts, as with everything, you get more bees* with honey than vinegar. Calling people names gets you precisely nowhere. You have to tailor your spiel for the audience. If you can't think like a salesman you have precisely no place in a communications leadership post. Obviously, I dislike sales as much as anyone else, but I find myself in the rather privileged position of begrudgingly being a salesperson right now.
In sales, you have to get to know your audience, what they enjoy about the product they are currently using (their religion) and use that to show why your solution is so much better. You can't just explain the logical, rational reasons why your solution is better, you have to emote. It helps if you truly believe your solution is better. I once had to sell phone lines on the phone. "Hi there, do you want a phone line? Oh you've got one haven't you. I'm ringing you on it." Two days I lasted. Two days. I made one sale which I wish I hadn't because it was a lovely old lady who didn't understand what I was selling and just went along with it. The Vultures jumped right on the poor dear. I quit right then and there.
Anecdotes aside, Dawkins is an a..eh.le, pure and simple. And unfortunately, far too many public atheists and humanists are patronising and insulting to people with Beliefs, and a lot of them don't seem to realise they're doing it. I know you guys won't, so here's Nezumi's Reluctant Guide to Selling Stuff to People (this also reads like a manual for making people join your cult. Same techniques apply.)
1: Know your audience. Build rapport by actively listening, ask pertinent questions, look interested. While doing this consider how you can position your product as the superior choice.
2: Be a human being, but be a good one. Be sympathetic, be kind, this is where cults start love bombing. Don't do that. Be more like a counsellor - unconditional positive regard goes a very long way here. Find ways to subtly promote your product. DO NOT DENIGRATE THE CURRENT CHOICE. EVER. Be positive about your direct competitors, have some grace for pity's sake
3: Listen for "buying cues". These are subtle ways your customer will hint their interest. Use those to draw them in. Invite them to a coffee morning or a free trial or whatever it is you're trying to sell.
4: Remain positive throughout. Use above the line language (ie. business jargon for positive phraseology) and act a little bit enthusiastic (not too much!) to have them on board.
5: After sale care is the most important part of your process. If it's a product, a courtesy call to check everything's ok. If it's an ongoing relationship then act as a guide for your recruit, make sure they are introduced to positive people and that the group takes an interest in them. Be welcoming. Accept current beliefs. No point challenging them outright when you now have them in a peer group that believes the new stuff. The environment will do the work, your job is to help people be comfortable within that environment.
FYI I am quite good at sales, for my sins.
* Or flies, if you're my Gran.