They are not really secret.
Psalm 10:11 He hath said in his heart, God hath forgotten: he hideth his face; he will never see it.
Psalm 94:7 Yet they say, The LORD shall not see, neither shall the God of Jacob regard it.
Jeremiah 23:24 Can any hide himself in secret places that I shall not see him? saith the LORD. Do not I fill heaven and earth? saith the LORD.
Jeremiah 16:17 For mine eyes are upon all their ways: they are not hid from my face, neither is their iniquity hid from mine eyes.
Psalm 90:8 Thou hast set our iniquities before thee, our secret sins in the light of thy countenance.
Ecclesiastes 12:14 For God shall bring every work into judgment, with every secret thing, whether it be good, or whether it be evil.
Romans 2:16 In the day when God shall judge the secrets of men by Jesus Christ according to my gospel.