“For you were bought at a price; therefore glorify God in your body and in your spirit, which are God’s.” (1 Corinthians 6:20 NKJV)
Such grace is costly because it calls us to follow, and it
is grace because it calls us to follow Jesus Christ. It is costly because it
costs man his life, and it is grace because it gives a man the only true life.
It is costly because it condemns sin, and grace because it justifies the
sinner. Above all, it is costly because it cost God the life of His Son;
"you were bought with a price," and what has cost God much cannot be
cheap for us. Above all, it is grace because God did not reckon His Son too
dear a price to pay for our life, but delivered Him up for us.
Bonhoeffer in “The Cost of Discipleship”