The latest one will be unveiled next weekend, as the artist gets down to work after 'crowd source' discussions with a team of people earlier this week.
The murals are painted eight times a year and comment on issues in the church or the wider world with the aim of being challenging and prophetic.
As a side effect they are often controversial, provoking dialogue and sometimes friendship between groups. In the month of August, the St John's mural is incorporated into the festival.
Various ideas for this year's festival mural were tossed around, from Scottish Sectarianism to the uprising in Syria, before the obvious conclusion was arrived at: this summer's main event, the London Olympics.
Unfortunately, the controversies surrounding the Olympics are a thousand-fold. To name just two, the issue of the Palestinian athletes was discussed, as was the marked contrast between London 2012 and the riots of summer 2011.
Ultimately, what most captured our interest was the landmark status of the 2012 Olympics as the first time every participating country has allowed female athletes to compete. This is a victory for women's rights worldwide and the festive month of August seemed like an appropriate time for a celebratory message.
This message is broader than its athletic context; the festival mural will highlight gender issues in general and in particular will tackle the notion than feminism is a western phenomenon. We also wish to show women as vital to development and progress.
The theme of this month's mural will therefore be 'Race for Equality'. We plan to show a relay race of women from around the world beating out competing figures such as poverty, repression and lack of education, emphasising the importance of perseverance and teamwork to not only this summer's victory but feminism as a whole.
The mural will be painted on Friday 10th and Saturday 11th August and will be available to view until the end of the Festival. The Facebook page for the St John's Murals can be found here.