The Christian ministry building a Noah's Ark theme park sued Kentucky tourism officials Thursday, saying they violated the group's free speech rights by denying them an $18 million tax incentive.

The incentive was meant for the Ark Encounter, a theme park plan that will be built in phases around a 500-foot-long wooden ark modeled after the Bible's story of Noah. State officials said in December that the project's mission had changed from tourist attraction to ministry, and denied the benefit.

In the lawsuit, the Answers in Genesis ministry said religious beliefs should not prohibit the group from participating in the tax incentive plan. The suit names the tourism cabinet and Gov. Steve Beshear.

Kerri Richardson, a spokeswoman in Beshear's office, said officials had not seen the suit and declined to comment.

The incentives were rejected "solely because of our religious identity and the biblical messages we will present at our future life-size Noah's Ark," Answers in Genesis president Ken Ham said in a release.

Critics of tax incentives for the ark park have also cited potential constitutional violations, saying the state should not be giving money to a group that will practice discrimination in hiring. The Washington-based Americans United for the Separation of Church and State had threatened its own lawsuit before the state withdrew the tax benefit.

The ministry is asking a federal judge to compel tourism officials to place the ark project back into the incentive program.

Kentucky Tourism Secretary Bob Stewart said in a December letter that the state could not provide incentive money to an attraction that would screen hires for religious preference and proselytize to visitors.

The 48-page lawsuit argues that Answers in Genesis can do just that. It says "a ban on religious proselytizing would be unlawful, as well as impossible to enforce." And due to a change in structure that put it under the ownership of a non-profit, the theme park has the right to show a preference for applicants who share the ministry's strict beliefs, the suit says.

It's those beliefs that have drawn much attention for the ministry, beginning with its Creation Museum that opened in northern Kentucky in 2007. The $27 million facility built on private donations promotes a strict interpretation of Old Testament stories and has exhibits showing dinosaurs and humans living together.

The lawsuit also argues Kentucky's action violates religious freedoms protected by the First Amendment, along with the equal protection clause of the 14th Amendment and state laws.

Answers in Genesis said the loss of the tax incentive hampers future building phases of the ark project.

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