2 Timothy 1:10-12

2 Timothy 1:10-12. But is now made manifest by the appearing of our Saviour Jesus Christ, who hath abolished death, and hath brought life and immortality to light through the gospel: Whereunto I am appointed a preacher, and an apostle, and a teacher of the Gentiles. For the which cause I also suffer these things: nevertheless I am not ashamed: for I know whom I have believed, and am persuaded that he is able to keep that which I have committed unto him against that day.

Paul knew that grace could keep his soul, but I think that he here means that he could keep his own gospel. Paul had kept it, kept the faith, but he committed it now into the hand of the greater One, who would keep it when every apostle was dead, and every faithful witness had passed away. "He is able to keep that which I have committed unto him against that day."