Who is the 'one' in Romans 5:15 through whom the offense came?
The 'one' in Romans 5:15 is Adam. The context says that through the offense of one, many are dead, and then explicitly identifies that one as Adam. His offense is contrasted with the free gift, which is much more, as Scripture states.
Les explains that Romans 5:15 is still discussing Adam. He says, 'now remember what we're talking about, this is Adam,' connecting the 'one' whose offense brought death to many with Adam. Les also notes the contrast: just as through the offense of one many are dead, much more the free gift. He points out that all born of Adam should be in glory, because none are left out, yet he raises the question of why they will not be. The surrounding context about Jewish believers and the body of Christ shows that Jew and Gentile are all one in Christ, but the specific 'one' in verse 15 is Adam.
But not as the offence, so also is the free gift. For if through the offence of one many be dead, much more the grace of God, and the gift by grace, which is by one man, Jesus Christ, hath abounded unto many.
More Questions
Does calling Jesus 'one man' in Romans 5:15 mean He is not God?
Paul's phrase 'one man, Jesus Christ' does not deny Jesus's deity; it agrees with the virgin birth, because Jesus was born God in the flesh but also born human, making Him the God-man.