Why are past-lives important?
To understand yourself you have to understand your past. That includes your past lives, you won’t make much sense of this life if you don’t understand the ones you had before. The person you are now may have been formed over many lives. Good and bad traits may have grown through multiple reincarnations. What you discover about yourself in this sort of work is not always easy. Some people take a view that it is about becoming comfortable with yourself and that we will naturally develop into the best of all possible you. That is not our view, our view is that as an adult you are responsible for what you do and what you did. Good and bad, it is you and you better deal with it. The Universe isn't going to fix what is your job to do. So past-life work is not always easy. But you understand yourself better if you get those memories back.
Intention matters here. If you believe that you have been and will be, that you will eventually be reborn then the work you do on yourself is the legacy you leave to the future. You can't leave them material wealth but you can leave them a spiritual legacy. We believe that matters.
One of the objectives of Mithraism is therefore personal growth and understanding of ourselves through the recovery of the self. It is not the only reason to explore past lives but it is a good one. It may have immediate advantages, for example a person who has a phobic response to fire might recovers memories they died in a house fire in a previous life. It doesn’t take the fear away and it doesn’t automatically cure the phobia but at least it gives context, makes it easier to understand and therefore deal with. It’s what you don’t understand about yourself that really messes you up. In the end the responsibility for you is yours and choosing to do nothing about it is still a choice.
We also carry spiritual links through our reincarnations. These can be people that you encounter in several lives because you are joined by the bonds of love and friendship. Understanding the depth of a relationship can add to the ones you have now. It is quite possible to marry the same person repeatedly.
However understanding you have lived before has an important implication. You will live again.
That raises all sorts of consequences, for your personal spiritual health, ethics, the condition of the planet, to what you want to do with your life. This may be one of the middle chapters in the book of your life, but there will be others. What you do in this life will affect what happens next.