For the past few weeks, Brittany and I have been attending The Summit Church in North Raleigh, and J.D. Greear has been teaching about how to know that you have salvation.
The most interesting point the J.D. has made from 1 John 1:5-6 is that if you have been in darkness and you come into the light, you have a desire to retreat back into the darkness. The light is harsh and it makes you close your eyes until you adjust to the light. But once someone comes from the darkness into the light, you must be impacted by the light.
So many people who have an encounter with Christ are resistant to him. Christianity, like Paul said, is foolishness to those who do not understand. But to have an encounter with God is to be changed; if you believe that you are a Christian, you cannot live as if you are not one. If you live as if you are not a Christian, you probably aren’t one.
J.D. also points out that your goals and thoughts point to your assurance. If the things that are important to you do not involve Christ, you might not be saved. If your focus is on getting married/sports/drinking/money/your job/school and yet you cannot find time to focus on Christ, this shows that you think those things are heavy and Jesus is light. If you think much of the Los Angeles Lakers and little of Jesus, you might not be saved.
Finally, if you choose to obey the Bible in some parts (death of Christ, resurrection, etc.) but not in others (tithing, homosexuality, gossip, etc.), it shows that you have made Christ your savior, but not your Lord. If you have made Christ your Lord, it means that where you disagree with the Bible, then the Bible is right and you are wrong: this is the definition of Lordship. If this sounds like you, examine your heart and see if Jesus is Lord. Jesus is right and you are wrong.
I hope that you have given your life to Christ and seek to glorify him in all that you do; but if you have not, the Lord asks that you to lay down your life in submission to him; acknowledge that Jesus is the payment for your sins and that you will serve Him because of his love for you.