The Greek that is translated as “to you has been given the secret of the kingdom of God” or similar in English is translated in the German New Testament translation by Berger / Nord (publ. 1999) as unter euch ist Gottes Herrschaft unsichtbar, als Geheimnis, gegenwärtig or “God’s reign is present among you, invisibly, as a mystery.”

In a footnote they explain: “Literally: ‘The secret of the kingdom of God has been given to you.’ This does not refer to understanding, because the disciples clearly still lacked that. The word ‘mystery’ [or: secret] refers to the state of the kingdom, not to the disciples’ knowledge.”