The banners have appeared on staircases, escalators and platforms at 400 locations across the London Underground network for two weeks.
Chief marketing and communications officer at Alpha International, Cam Watson said the beginning of January is a "natural" time of year to highlight the evangelistic programme.
He told Premier: "You probably heard in the news this week, statistically, more people are depressed at this time of year and the divorce rate goes up... it's a natural time for us to be saying 'you know what? There is more life."
Alpha International said it bought left-over advertising space from Transport for London at a cut-price.
The organisation, which was established by Holy Trinity Brompton in London, hopes advertising its course on public transport will reinforce posters on display at 9,500 churches which run Alpha.
Cam Watson went on to say: "We hope that over the next couple of weeks, they [commuters] will see signs about Alpha a few times.
"Hopefully during that time, they also might get invited to come on Alpha by someone they know and it will all click together."
The posters form part of a global Alpha campaign spanning 200 countries including Malaysia, Poland and South Africa.
Cam Watson added: "My guess would be most of us have got someone we've been praying for, for years - whether it's been a family member or a friend from school or even someone you met at the supermarket last week.
"I'd really encourage your listeners to take that step, to invite someone to find an Alpha running in their area."
Click here to listen to Premier's Eno Adeogan speaking with Cam Watson at Alpha International: