Not by just any random sin committed in a moment of weakness or inadvertantly, but if I were to choose deliberately to walk away from God, and continued in that, then yes, I could lose it.
I know that the next question is "were you ever really saved in the first place"? You have to define what viewpoint you're working from. If you are looking at it from God's viewpoint, then it could be said that no one who is truly saved can ever be lost, and no one who is lost can ever truly be saved. From yours and my own standpoint, living in linear time as we do, then we could sincerely believe we are saved, but if we walk away from it and never go back, then we "lost" our salvation.
From God's vantage point, the end is already certain, He sees it all as happening in the present. From our vantage point, we have to walk it out. So many times this point is argued, without the point of view being clearly defined. And whether you think so or not, it is a legitimate question for a person to ask, because what they're really asking is "How can I know I'm saved?", which is an indication that they truly want to receive, but they don't want to have run in vain. I think that is a legitimate concern, and we shouldn't bludgeon people over the head about it, but learn to listen to find the real question, and help them in love to see the truth. Love never fails.
Jesus answered them, “I told you, and you do not believe. The works that I do in My Father’s name, they bear witness of Me. But you do not believe, because you are not of My sheep, as I said to you. My sheep hear My voice, and I know them, and they follow Me. And I give them eternal life, and they shall never perish.” (John 10:25–28)
Now if they perished, our Lord was wrong.
Neither shall anyone snatch them out of My hand. My Father, who has given them to Me, is greater than all; and no one is able to snatch them out of My Father’s hand. I and My Father are one. (John 10:28–30)
The picture is this: Both are hands of Deity. Christ says, “No created thing can take them out of My hand, no created thing can take them out of My Father’s hand.” These are the two hands of Deity. You can’t get to the sheep that are in those hands. You just can’t!
“I give them eternal life. They shall never perish. Nothing can snatch them out of My hand.” That’s a tremendous statement, is it not? It’s an audacious statement!
BigMack