Once saved, always saved. What is so difficult to understand about the phrase "everlasting life"? You cannot loose "everlasting life", otherwise it wouldn't be everlasting.
My sheep hear my voice, and I know them, and they follow me: And I give unto them eternal life; and they shall never perish, neither shall any man pluck them out of my hand. - John 10:27-28
You can listen to preachers that preach things you like to here, but that does not make it true.