About 20 people demonstrated outside Cornerstone International Bible Church in Filleul St on Saturday.
Protest organiser Sam Bosshard said he believed the seminar hosts Dr Sheree Trotter and Perry Trotter were trying to debunk allegations Israel was an occupying state and had committed genocide in Gaza.
Mr Bosshard said the protesters were worried about pro-Christian Zionism, and Zionism was the "backbone" of the Israeli regime.
Zionism refers to the movement to recreate a Jewish presence in Israel.
Mr Bosshard said a small number of people attending the seminar were angry at their protest.
However, he and church member Sam Mangai, who was standing as security at the church’s Filleul St entrance, had struck up a good relationship and there were no issues.
Mr Mangai said the protesters were entitled to their opinions and both groups wanted peace.
He did not agree Zionism was a problem.
A webpage about the seminar said Dr Trotter would cover many of the competing claims concerning the ongoing conflict in the region and would address some of its historical and geo-political context.
Mr Trotter was the author of a book called Israel in the Biblical Worldview and he had "experience refuting replacement theology and Christian anti-Zionism".
Replacement theology refers to a view the Christian church has replaced the Jews as God’s chosen people.
The all-day seminar would examine if it was "really true that Israel is a white European coloniser, guilty of occupation, apartheid, ethnic cleansing and genocide against the indigenous Palestinians".
The duo is hosting another seminar in Invercargill at Tay St Baptist Church on Saturday.
