Once Saved Always Saved

"ONCE SAVED ALWAYS SAVED" IS this: ..".HE (SHE) THAT "SHALL" (WILL) ENDURE UNTO THE END SHALL (WILL) BE SAVED..." (Matthew 24:13 KJV). ETERNAL LIFE IS THE DESTINATION, BUT ENDURING WITH JESUS, WHO IS THE ONLY"WAY," OR IS THE ONLY "PATH" TO THE DESTINATION DEPARTING FROM THE "WAY" IS A DEPARTURE FROM THE "PATH" TO THE DESTINATION (ETERNAL LIFE). Are you sure that once saved, you are always saved?