As I find myself in a discussion over "once saved always saved," I wonder why some people struggle with this. I think of what Jesus did for me (and all of you), by sacrificing Himself on the cross for my sins, and I find myself humbled and wanting to show Him my gratitude. I feel the need to turn away from my sin and try to live a life pleasing to Him. After salvation, we all will slip up and fall into sin, but when we do, we should have great remorse and want to repent.
When we truly love someone, we want to please them. Salvation in about a life change, not just saying the words and then going back to the way you were living. I don't, and never have thought "I'm saved, now I can do anything I want." If you have these thoughts, take time to re-examine your heart.
For the gifts and the calling of God are irrevocable.
Once you have placed your faith in Him, God will never cast you away. He will never abandon you, reject you, or turn you away. As a loving Father, He will discipline you, but He will never throw you away.