YEs I believe in an eternal spirit.
Do I have proof. No.
Is there a chance that there isn't one. Yes.
Same as God.
Do I believe in God. Yes.
Do I have proof. No.
Is there a chance that there isn't one. Yes.
I do think however that where you find one, you will find the other. And if you don't find one, you probably won't find the other.
Definition of spirit is preservation of your essence. So there are a number of possibilities after that - with memories, with no direct memories; within the realm of the mind of God so to speak. All that matters is that an essence of ourselves is preserved and that this life is real and that what we do matters and has consequences.