The phrase "to promote the idea" means to support or encourage a particular concept or belief, and to try to get others to agree with or adopt that concept or belief. Full definition
Its first major initiative in the education arena was an attempt to boost high school graduation rates by promoting the idea of smaller schools. (governing.com)
Private schools and universities have a vested interest in promoting the idea that more education — and more expensive education — will help your child get ahead. (moneysense.ca)
Although their motivations may differ, each side has reasons for promoting the idea that sexual activity is freely chosen behavior. (firstthings.com)