This is a great question and a biblical question.  It is asked several times in the New Testament in various ways.

Mark 10:17 - And when he was gone forth into the way, there came one running, and kneeled before him, and asked him, Good Master, what shall I do that I may inherit eternal life?

Acts 2:37 - Now when they heard this, they were pricked in their heart, and said unto Peter and to the rest of the apostles, Men and brethren, what shall we do?

Acts 16:30 - And brought them out, and said, Sirs, what must I do to be saved?

    If the Lord were to come today, would you know that you are going to heaven?

What Does the Bible Say?