Our Lord said that a Great Delusion “will come upon them that would be so strong that it will even effect the elect.”
Close - it says “if it were possible”.
So it’s not possible for us to be deceived. Why not?
Mark 13:22
For false Christs and false prophets will appear and perform signs and wonders that would deceive even the elect, if that were possible.
Matthew 24:24
For false messiahs and false prophets will appear and perform great signs and wonders to deceive, if possible, even the elect.