Ahn was born in South Pyongan Province as the first son of a traditional doctor.
Although this was interrupted, he continued his studies in sociology with a minor in religion at Seoul National University (1946–1950).
He then pursued a PhD (1956–1965) at Heidelberg University under the supervision Günther Bornkamm, a student of Bultmann, completing a dissertation on "Das Verständnis der Liebe bei K'ung-tse und bei Jesus" (Understanding Love in Confucius and Jesus).
[3] Ahn argued that, in the Gospel of Mark, Jesus was always on the side of the ochlos, the "crowd" who were marginalized and dehumanized.
Ahn believed that German historical-critical exegesis neglected the place of the ochlos, and yet Jesus's ministry was focused on creating the Kingdom of God with this marginalized crowd.