What distinguishes a gift from something you earn?
A gift is something given freely out of the goodness of the giver's heart; the recipient does not deserve it, work for it, or merit it. By contrast, earning implies doing something to deserve payment. Scripture presents salvation as a gift by grace, so adding works contradicts its very nature as a gift.
Les explains that the Scripture makes plain that salvation is a gift, and if you think you have to work for it, you are flying in the face of this Book. A gift, by its nature, is not something you deserve, work for, or merit; it is something someone has done for you out of the goodness of their heart. That is what God has done for the human race out of the goodness of His heart. He has given it as a gift, but people turn around and say they will work for it, and He will not stand for it. The gift by grace is by one man, Jesus Christ, and it has abounded unto many. Les notes that Paul refers to Christ as the man, not taking away from His deity, but recognizing the God-man, born of the virgin birth, God in the flesh yet human.