The following is from Grace to You (Blog):
I remember exactly where I was when I discovered some Christians believe eternal life may not always be eternal. The moment is still etched in my memory.
Shortly after I was saved, a friend invited me to a midweek Bible study at a local church. During the course of our study, one fellow asked, “How can someone know if he has lost his salvation?” As discussion ensued, it became clear he was talking about himself. This poor man thought he was in danger of losing his salvation.
That was the first time in my Christian life I had personally encountered someone who was sincerely afraid of losing his salvation. And even as a young believer, I believed once you were saved, that was it—your hope of eternal life is secure and certain. I mean, it is eternal life, isn’t it?
Read more: http://www.gty.org/blog/B110315/is-eternal-life-always-eternal
More in this series:
How Firm Our Foundation
Once Saved, Always Saved?
The Saint's Guarantee - John MacArthur
12 Questions For Those Who Believe Salvation Can Be Lost – Pulpit & Pen
Eternal Security and Problem Passages by David Cloud (Way of Life)
Can A Christian Lose His Salvation? Hebrews 6:4-6 - J Vernon McGee - FULL Sunday Sermons