What does Les mean by personal salvation?
Personal salvation means Christ died for each individual, not merely for humanity under a general umbrella. If you were the only person on earth, Christ would still have gone through the work of the cross. Therefore salvation becomes an individual responsibility to believe the gospel.
Les explains personal salvation by stressing that Christ did not put the human race under an umbrella; He died for every individual. Even if you had been the only person on earth, Christ would still have gone through the work of the cross. That is why salvation becomes an individual responsibility to believe the gospel. This fits the surrounding point that Abraham believed God, and his believing was counted unto him for righteousness.