What is required for salvation according to Paul in this passage?
According to Paul, salvation requires understanding that Christ, the Son of God and Creator God, went to the cross and died for our sin, and then rose from the dead. Knowledge of His earthly ministry—Bethlehem, miracles, suffering—is good but not what is required.
Les explains from this passage that because Christ died and rose from the dead, His earthly ministry is not what has primary importance for us. Les says it is good to know about Bethlehem, Christ's miracles, and His suffering, but those things are not what is required for salvation. What is required, he teaches, is understanding that this Christ—the Son of God, the Creator God—went to the cross and died for our sin, and that He rose from the dead. This contrasts with knowing Christ merely “after the flesh,” meaning His earthly ministry.
Wherefore henceforth know we no man after the flesh: yea, though we have known Christ after the flesh, yet now henceforth know we him no more.