Staring in 1939, all German boys were required to join. It was not optional. If he did not join, he probably wouldn't have been shot, but would likely have been taken away from his parents.
JOSEPH RATZINGER was born in Marktl am Inn, Bavaria, in 1927, and grew up under Hitler’s shadow in the Thirties. His family was anti-Nazi, but not involved in resistance; his father, a policeman, accepted assignments in progressively smaller towns in order to stay clear of politics. The young Ratzinger drew inward, immersing himself in the florid Bavarian piety of the era. In later reflection on the war and Nazism, many German theologians of Ratzinger’s generation, such as the famed moralist Bernard Häring, saw the dangers of blind obedience as its central lesson, fuelling a reform streak in German Catholicism. Ratzinger, however, drew a different conclusion. Only a Church with a strong central authority and rock-solid doctrinal verities, he concluded, can withstand a hostile state or culture. This conviction – one he shares with Pope John Paul II – has informed much of his later Vatican career.
I don't want to be too hard on the guy. It's really easy to judge effortlessly from present vantage point, but even though resistance would have meant death, if everyone felt that resistance was thus futile, then hitler would have indeed succeeded. So, while I guess the desire for self-preservation is understandable, God bless those who didn't let that be their first consideration.
'Ratzinger, a staunch conservative dubbed "God's Rottweiler," has said he joined the Hitler Youth when membership became compulsory. He and his brother were later drafted but deserted. The cardinal claims he never fired a shot and that resistance would have meant death.'