Graeme Goldsworthy gives a stirring answer:
Predestination, or creation, or the new birth, or the baptism o the Spirit is not…the gospel. All of these things are related to the gospel and are necessary for the working of the gospel, but they are not the essential message to be believed for salvation. Furthermore, unlike the gospel message, they do not directly address the matter of our justification and assurance of salvation. Only the message that another true and obedient human being has come on our behalf, that he has lived for us the kind of life we should live but can’t, that he has paid fully the penalty we deserve for the life we do but shouldn’t–only this message can give assurance that we have peace with God through our Lord Jesus Christ.
– Graeme Goldsworthy, Preaching the Whole Bible as Christian Scripture (Grand Rapids, Mich.: Eerdmans, 2000), 83-84.