The resurrection of Jesus means first of all that God loves all of humanity, excluding no one, and that is why we have the command to go into all the world and proclaim the good news to the whole of creation. Christ can never be just one more religious leader among a myriad of others. He is and always will be the good news that all are now reconciled in him to the God whose love is proven by what Jesus, the Son of God, did. This is good news we have no right to keep to ourselves. Unbelief separates us from Christ and hence from God.
Unbelief presupposes the opportunity to believe.
What we are to believe is that Jesus has been raised up from the dead, and we are to believe in what this means. It means reconciliation with God, but also reconciliation with all of humanity, even with all of creation. This is the good news that gives hope to all. But all of us are called to be the Body of Christ and as such to give witness to our faith in Jesus Christ because our hope is in his resurrection, his victory over sin and death. Our joy is to know that others come to know this good news too.