Dawood Zwink, executive director of the Michigan Muslim Community Council, charged that Spencer's presentations are "incendiary" and "not in keeping with American values of civil dialogue."
"I think it's sad to see that this group would try to stage this kind of confrontational encounter, when Catholic and Muslim leaders are engaged in an ongoing, cordial dialogue," Zwink told the Detroit Free Press.
Spencer said his critics were off-base.
"It would be nice for someone to have the courage to say that there is nothing wrong with resisting jihad violence and Islamic supremacism, but that may be too much to hope for in today's politically correct age," he wrote on his blog.
In January the Diocese of Worcester, Mass., withdrew an invitation to Spencer to speak at its annual Catholic Men's Conference after Muslim groups raised concerns. In July the Diocese of Sacramento canceled a scheduled speech on church property.
Bishop Earl Boyea of Lansing, Michigan is scheduled to celebrate Mass at the end of the symposium, drawing some criticism from local Muslim leaders.
Bishop Boyea's office said in a statement that the bishop "neither endorses nor condemns any of the featured presenters" and hopes that the symposium can help spur "what Pope Francis last week called 'mutual respect through education' between Christianity and Islam."
Ave Maria Radio's announcement for the conference cites a Pew Forum on Religion and Public Life survey which found that 19 percent of U.S. Muslims said that suicide bombing or other forms of violence in the name of Islam could be justified.
Kresta said that some critics of Spencer's appearance seem not to have confidence in the ability to refute him.
"Otherwise wouldn't they want the opportunity to publicly expose his 'hate-mongering' and 'Islamophobia'?" he asked. "It won't do in a principled pluralistic society to hive off into our ethnic or religious ghettos and accuse outsiders of hatred and bigotry when we haven't even confronted them publicly."
"Those attending will better understand each side and will be less willing to hastily prejudge one side or the other. For heaven's sake, this is a public debate not a one-sided propaganda fest. We must get beyond cliches if we are to live together with irreconcilable differences."
(Story continues below)
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