Buttars last August asked the State Board of Education to insert in curriculum language that humans didn't evolve from any other species. He also had publicly suggested that if students were learning human evolution, they be required to learn about intelligent design — or the idea that life is too complex to be explained by Darwin's theory alone — in a humanities or other class outside of science.

But instead, the board unanimously passed a position statement supporting evolution in the curriculum and telling teachers to respect students' beliefs.

Buttars vowed he would pursue legislation on the matter.

Friday's debate was peppered with religious references, and defenses.

Sen. Parley Hellewell, R-Orem, who supports the legislation, told senators, "It's important we stand up and fight for what we believe."

"I will not be cowed into silence by threats from those using the R word (religion)," said Sen. Allen Christensen, R-North Ogden. "I take exception to this theory as being totally accepted fact. It is not."

Sen. Sheldon Killpack, R-Syracuse, said, "I'm amazed that this religion of atheism and secularism, they are so nervous about being able to simply say, not everyone agrees on this (theory). . . . The slippery slope is that religion's imposing view that we can't have a belief in God. I find that offensive, personally."

Faith also entered Knudson's speech opposing the bill.

"I don't have any doubt in my mind about the existence of God . . . or creation of Earth by God, or our Father in Heaven. (What I don't know is) how God created the Earth, how God created his creatures and all that is created therein," Knudson said. "There is a place in life for evolution — it's part of life. The whole principle of being born, gaining experiences and leaving this Earth is purely evolution in one context or another. It saddens me that one's faith would be challenged on a vote on this bill. I vote no."

Science also played a role in the debate.

Sen. Karen Hale, D-Salt Lake, noted scientific theories are developed after repeat testing, observation and data and are far more complicated than an educated guess or the common usage of the term. She questioned whether the bill would require students discuss the origins of life, which is not part of the state core curriculum.

Sen. Scott McCoy, D-Salt Lake, unsuccessfully proposed amendments to replace references to the origins of life or "present state of the human race" with "scientific" theory. So, the bill would encourage students to critically analyze scientific theories, from relativity to plate tectonics.