If you work in advertising, you're in the business of ideas. Apple sells laptops. Braun sells toasters. Ford sells trucks. You sell ideas.

Selling ideas is difficult. Ideas aren't tangible like laptops, toasters or trucks. Clients can't test-drive them before they buy them. Instead, they have to trust that you possess the ability to bring the ideas they're buying to life. In a way, they aren't buying the ideas. They are buying you.

Creatives don't like to sell. They see it as unnatural. Unholy, even. However, it's worth remembering that Jesus had twelve Apostles. They were sent out to preach on his behalf. One could argue that preaching is selling Christianity; and that selling any sort of religion is just as intangible as selling ideas.

Religious texts are full of stories. I think that's how you sell ideas. You must believe in your ideas. If you don't believe in them, nobody else will. Then, you must tell a beautiful story about why they should believe in your ideas too.