Belief in the existence of God and belief in the existence of extraterrestrial life are two separate concepts and are not necessarily linked. People who don't believe in God can hold a variety of views regarding the existence of alien life.
The question of whether or not there is extraterrestrial life is a scientific and philosophical one. It is based on our understanding of the universe, the conditions necessary for life to exist, and the likelihood of those conditions occurring elsewhere. Many people who do not believe in God still entertain the possibility of the existence of extraterrestrial life.
From a scientific perspective, the vastness of the universe, with its billions of galaxies and potentially habitable planets, leads many to speculate that it is highly probable that life could have arisen elsewhere. The discovery of exoplanets (planets outside our solar system) in the habitable zone of their respective star systems has fueled this speculation.
However, it is important to note that the question of whether or not there is alien life remains unanswered. As of now, there is no definitive evidence of extraterrestrial life. Scientists continue to explore and search for signs of life beyond Earth through methods such as the search for microbial life on Mars or the detection of biosignatures in the atmospheres of exoplanets.
Beliefs about the existence of God and the existence of alien life can vary greatly among individuals, and one's position on one topic does not necessarily dictate their position on the other. These are complex and multifaceted questions, and different people may arrive at different conclusions based on their personal beliefs, scientific understanding, and philosophical perspectives.