To examine the influence of different actors' fictitious statements about research and deployment of stratospheric aerosol injection (SAI), we conducted an online survey in Germany. Participants assess researchers and a citizens' jury to be more credible than politicians. Credibility has a strong positive effect on SAI acceptance in both pro-SAI and contra-SAI conditions. Reading the statement against SAI-deployment led to significantly lower acceptance scores compared to reading the pro-statement. However, the difference between messages was unexpectedly small, indicating that the message content was not fully adopted while underlying traits and attitudes mainly shaped acceptance even despite, or because of, low levels of knowledge.