I wouldn't want to assume the details or the difficulty someone else has or is going through related to this.
What I have found helpful, when I went through something like this, is to distinguish between the "feeling" of certainty and the "choice" to put my faith in something. A lot of the time, we talk about "faith" and we conflate those two. I can choose to trust something and not feel confidence in it until after the fact. How much confidence I feel in a choice varies for a lot of reasons, but I may still choose to accept the risk and act on the little information I do have because I don't have better alternatives.
In that sense, you can choose what you believe. Or at least, you can choose what you put your faith in.
What I have found helpful, when I went through something like this, is to distinguish between the "feeling" of certainty and the "choice" to put my faith in something. A lot of the time, we talk about "faith" and we conflate those two. I can choose to trust something and not feel confidence in it until after the fact. How much confidence I feel in a choice varies for a lot of reasons, but I may still choose to accept the risk and act on the little information I do have because I don't have better alternatives.
In that sense, you can choose what you believe. Or at least, you can choose what you put your faith in.