You are looking into the future, not at the moment for which the questions were asked. Satan was influencing Peter when he thought he was smarter than Jehovah Jesus Christ.
No, I'm looking at exactly the time when Messiah said those words. You could argue the adversary is influencing yourself at times, or anyone else. Messiah already testified about the Eleven Apostles sans Judas, to the Father, and they are all witnesses. We are witnesses when we read the scriptures. All that remains is to believe through their word. They were already saved at that time and, of course, had many trials to overcome and endure, as do we.
Blessed be the God and Father of our Lord Jesus Christ, which according to his abundant mercy hath begotten us again unto a lively hope by the resurrection of Jesus Christ from the dead, To an inheritance incorruptible, and undefiled, and that fadeth not away, reserved in heaven for you, Who are kept by the power of God through faith unto salvation ready to be revealed in the last time. Wherein ye greatly rejoice, though now for a season, if need be, ye are in heaviness through manifold temptations: That the trial of your faith, being much more precious than of gold that perisheth, though it be tried with fire, might be found unto praise and honour and glory at the appearing of Jesus Christ: Whom having not seen, ye love; in whom, though now ye see him not, yet believing, ye rejoice with joy unspeakable and full of glory: Receiving the end of your faith, even the salvation of your souls.
-- 1 Peter, in the Catholic chapter one, Protestant verses three through nine, as authorized by King James
Humble yourselves therefore under the mighty hand of God, that he may exalt you in due time: Casting all your care upon him; for he careth for you. Be sober, be vigilant; because your adversary the devil, as a roaring lion, walketh about, seeking whom he may devour: Whom resist stedfast in the faith, knowing that the same afflictions are accomplished in your brethren that are in the world. But the God of all grace, who hath called us unto his eternal glory by Christ Jesus, after that ye have suffered a while, make you perfect, stablish, strengthen, settle you.
-- 1 Peter, in the Catholic chapter five, Protestant verses six through ten, as authorized by King James