>>> We can know that we will be saved if we so endure.
How can one know that they will endure?
Peter did not believe he would deny Christ 3 times, and yet Jesus knew that he would.
It is impossible for anyone to know that they will succeed or fail in anything.
Endurance is a work.
Salvation is by Grace not by works.
The sacrificial blood of Christ cannot be mingled with the filthy rags of man’s works.