God's measure of success for Noah was not how many sinners he saved from the Flood. If numeric results were God's measure of success, Noah would be a failure.
Genesis 6:1-4 summarize what led to God's rejection of the pre-flood civilization: men chose wives solely on the basis of sex appeal and external beauty.
God literally called Noah, offering him deliverance from the world catastrophe, and offering him a job of being a physical savior for all of creation.
It can be encouraging to us that our patriarchs and the prophets had serious doubts, but God overrode all their fears in accomplishing His purpose.
Both the 'eternal security' and 'no works' doctrines are destroyed by the remarkable example of Noah, who performed extraordinary works based upon faith.