Whereas I don't dispute that there is a hell, and I do believe in eternal life, I don't think avoiding hell or living forever should be what ultimately motivates us to do good, and to do the right thing. If it's all about 'winning the prize' or 'avoiding punishment', we are just doing what we do for our own sake. Christ didn't need to die on the cross to save his own soul. He didn't need to die on the cross to avoid hell. He sacrificed for us, because of love and because it is what he believed was right. At the very least we should do good things because good things are good. If when I die there is no afterlife, at least I will have tried to live my life in a way that means something - and not waste this gift of life, even though I've made so many mistakes and failed to do the right things along the way.
That said, I have often wondered about how a lack of belief in an afterlife affects your actions in this one. For those who believe this is all there is to their lives, and that there will be no more after they die, a focus on making ones life more comfortable in this world could definitely lead to being a bit more selfish and willing to fight for worldly things, like wealth and power.
It's a fundamentally important contributor to how you see life.
Your worldview dictates your reality.
I recall taking a ethics course where Peter Singer was the focus. Peter Singer was once head of Princeton's philosophy department. From a Christian worldview, this man postulated many evils. He taught that children who have not reached the age of self-realization; mentally retarded and others - do not have a right to life. Essentially, he believed many groups of people, young and old, could be aborted/killed for so-called ethical reasons. This man held a very sick worldview from a Christian perspective.
Where else have we seen worldview dictating morals? Nazism, communism and socialism to a lesser extent. In all three, we see the state justifying the murder or mistreatment of those the state considers a threat.
Yes, what one believes is important!
No, but it should always be there in the back of your mind.
*******************************************************
" I detest all my sins because of Thy just punishments, but most of all because they offend Thee, my God, Who art all-good and deserving of all my love. "