Church and art historians, and theologians at Amsterdam’s VU university are to carry out a major research project into the involvement of Protestant churches in slavery and colonialism, Trouw reported on Tuesday.

The Protestant church organisation PKN is cooperating with the investigation to ‘come clean’ about its past, the paper said. Churches benefited enormously from slavery, via donations from slave and plantation owners, and sometimes missionaries to Suriname were paid in enslaved people.

Visible signs of slavery in churches include gravestone carvings, and caricatures of black people on paintings and stained glass windows. But the project will also focus on looking at how thoughts about slavery and racism developed within the church itself, theologian Heleen Zorgdrager told the paper.

This summer, the leaders of the four big Dutch cities wrote to parliament urging the next cabinet to do more to shine light on the Netherlands’ ‘hidden and difficult’ slave trade history.

‘The stories of slavery and colonial history must be spoken about openly,’ the council chiefs of Amsterdam, The Hague, Rotterdam and Utrecht are quoted as saying in their letter. The options include a public holiday on July 1, national research into the country’s colonial past and a specialist agency to combat racism and discrimination

In 2023, it will be 150 years since legislation to abolish slavery was actually enacted in the Netherlands.