If we take our earthly existence out of the picture for a moment, and just look at eternity, everyone believes in eternal security.
Either in heaven or hell, once you're there, you're secure. And I doubt there's anyone here who would say, "no, you can be kicked out of heaven."
But looking back at our time on earth up to the point of death, Paul's words are sufficient:
Now He who establishes us with you in Christ and has anointed us is God,
who also has sealed us and given us the Spirit in our hearts as a guarantee. - 2 Corinthians 1:21-22
http://www.biblegateway.com/passage/?search=2Corinthians1:21-22&version=NKJV
For we who are in this tent groan, being burdened, not because we want to be unclothed, but further clothed, that mortality may be swallowed up by life.Now He who has prepared us for this very thing is God,
who also has given us the Spirit as a guarantee. - 2 Corinthians 5:4-5
http://www.biblegateway.com/passage/?search=2Corinthians5:4-5&version=NKJV
In Him you also trusted, after you heard the word of truth, the gospel of your salvation; in whom also,
having believed, you were sealed with the Holy Spirit of promise,who is the guarantee of our inheritance until the redemption of the purchased possession, to the praise of His glory. - Ephesians 1:13-14
http://www.biblegateway.com/passage/?search=Ephesians1:13-14&version=NKJV
And do not grieve the Holy Spirit of God, by whom
you were sealed for the day of redemption. - Ephesians 4:30
http://www.biblegateway.com/passage/?search=Ephesians4:30&version=NKJV
