I always thought that discovering life on other planets would challenge bible believers to the point of reconsidering how life really began......but I don't feel that way anymore. I don't think it would phase them ( at least the majority of them). Untill we find little men with big heads who look like ET, they won't be phased......and then they still no doubt will continue to believe an old books explanation.
People believe what they want to believe in spite of evidences. The witnesses taught me that.