"As the worker studies the life of Christ, and the character of His mission is dwelt upon, each fresh search will reveal something more deeply interesting than has yet been unfolded. The subject is inexhaustible. The study of the incarnation of Christ, His atoning sacrifice and mediatorial work, will employ the mind of the diligent student as long as time shall last; and looking to heaven with its unnumbered years, he will exclaim, “Great is the mystery of godliness!” [ 1 Timothy 3:16 .] GW 251.1"
"And without controversy great is the mystery of godliness: God was manifest in the flesh, justified in the Spirit, seen of angels, preached unto the Gentiles, believed on in the world, received up into glory."
Ellen White directly references 1 Timothy 3:16 in this passage.