Although many scientists agree that evolution does not make claims about God/god(s), students might assume that evolution is atheistic, and this may lead to lower evolution acceptance. In study 1, we surveyed 1081 college biology students at one university about their religiosity and evolution acceptance and asked what religious ideas someone would have to reject if that person were to accept evolution. Approximately half of students wrote that a person cannot believe in God/religion and accept evolution, indicating that these students may have atheistic perceptions of evolution. Religiosity was not related to whether a student wrote that evolution is atheistic, but writing that evolution is atheistic was associated with lower evolution acceptance among the more religious students. In study 2, we collected data from 1898 students in eight states in the United States using a closed-ended survey. We found that 56.5% of students perceived that evolution is atheistic even when they were given the option to choose an agnostic perception of evolution. Further, among the most religious students, those who thought evolution is atheistic were less accepting of evolution, less comfortable learning evolution, and perceived greater conflict between their personal religious beliefs and evolution than those who thought evolution is agnostic.