It’s like a change of clothing      

All mankind is naturally self righteous ……. trying to justify ourselves by what we do or what we have achieved. But when we receive, by faith, what Jesus has accomplished for us on the cross, we have no need for any righteousness of our own. Its like a change of clothes.

Jesus laid aside His heavenly glory, took on flesh and then gave Himself up to death in order to give us God’s righteousness. It could be called an ‘exchange’ of righteousness. This offer is free to all people without distinction because “all have sinned and fall short of the glory of God.”