The Church Investors Group (CIG), which is made up of 61 members including the pension fund for the Church of England and the Methodist Church, warned they would vote against board nominations where women account for less than 33 per cent of board members in the forthcoming annual meeting season.
Representative Stephen Beer, chief investment officer at the Central Finance Board of the Methodist Church, told Premier why the group was making threats.
"It's the right thing to do because for individuals...made equally in the sight of God, with equal worth - it's right that they have the same opportunities," he said.
The church group isn't the only organisation which has turned its attention towards improving gender diversity.
Tesco, which the group's members have invested in, is facing the UK's largest ever equal pay claim - with a bill potentially running to £4bn.
The supermarket giant is being taken to court by a group of mostly female shop assistants who have claimed male warehouse workers are earning more for doing a similar job.
However, Tesco on Wednesday insisted its wages are fair and said it works hard to ensure all staff are paid "fairly and equally".
Reflecting on The Church of England ordaining its first ever female bishop in 2015, Beer said its important for churches to also promote gender equality.
"Whatever the theological issues that churches have, they're all agreed that everybody is made equal in the sight of God," he added.
"We're all made in the image of God - male and female - and that should be reflected in wider society."
Outlining its new voting policy, the CIG said its members would also vote against executive pay packages where pay ratios are not disclosed, excessive pensions for chief executives or where financial services or pharmaceutical companies do not pay the living wage.
Listen to Stephen Beer, chief investment officer at the Central Finance Board of the Methodist Church, speaking with Primer's Tola Mbakwe:
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