Jesus doesn’t literally become a sinner, but he is literally punished for our sins because now he has them.
Through an act of faith, God “swaps” our sins for Christ’s righteousness, and that is why we can spend eternity with him.
But Protestant apologists like MacArthur will say our salvation comes not from anything we do, but from the simple recognition that Jesus has already done everything that is necessary to rid us from sin. On the face of it, this doesn’t sound like it has much to do with us needing only to make an act of faith in Jesus in order to be saved. “Some Protestants argue for justification by faith alone by appealing to 2 Corinthians 5:21, which says, “For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God.” Protestant pastor John MacArthur even calls this verse the “heart of the gospel” when it comes to belief in sola fide, or justification by faith alone. Crucifixion, Duccio di Buoninsegna (1308-11), Museo dell’Opera del Duomo, Siena, please click on the image for greater detail
