Some Christian communities talk about the “assurance of salvation,” an absolute certainty that one will go to heaven upon one’s death, regardless of how someone lives their life. The proposal sometimes sounds transactional: if I do X, God will do Y. (Often X means giving assent to the doctrinal formula of some particular group.) This may be justified by a scripture passage such as Acts 16:31. (They replied, “Believe in the Lord Jesus, and you will be saved—you and your household.”)
But the Catholic understanding of salvation is more nuanced. Jesus proclaimed that the reign of God is at hand. It is already here in our midst and yet still to come; it is the free gift of God and yet calls for our willing collaboration. Thus the best Catholic response to the question, “Are you saved?” is that we are being saved. We are assured that our God is a God who saves and that God’s saving action is constantly unfolding in the world and in our lives. A very thorough Catholic exploration of this idea can be found here: http://www.catholic.com/tracts/assurance-of-salvation.