'Hidden' in the Bible

on that day when, as my gospel proclaims, God will judge the secrets [all the hidden thoughts and concealed sins] of men through Christ Jesus.

I do not want you, believers, to be unaware of this mystery [God’s previously hidden plan]—so that you will not be wise in your own opinion—that a partial hardening has [temporarily] happened to Israel [to last] until the full number of the Gentiles has come in;