Found just twice in the New Testament (Rom. 11:33Rom. 11:33
English: American Standard Version (1901) - ASV
33 O the depth of the riches both of the wisdom and the knowledge of God! how unsearchable are his judgments, and his ways past tracing out!

WP-Bible plugin; Eph. 3:8Eph. 3:8
English: American Standard Version (1901) - ASV
8 Unto me, who am less than the least of all saints, was this grace given, to preach unto the Gentiles the unsearchable riches of Christ;

WP-Bible plugin), the Greek adjective “anexichniastos” meant “unsearchable,” past finding out,” or “incomprehensible.”

Paul used this term to say “perceptible history does not lead even to the tracks of the true ways of God” (Exegetical Dictionary of the New Testament, 1:97). Stated another way, our wisest and smartest ideas and plans are woefully inadequate to really grasp who God is and what He has done unless He reveals this information to us.