In the 2014 article referenced in this one, COL 69 is mentioned as central, or at least, often cited as evidence of this need to be sinless to allow Christ to come and take His people home. I mention this because I think it helps to expand on the context of this oft repeated phrase among SDA’s who see our perfection as necessary for God’s returning, and how it relates to the SS lesson under comment here by Mr. Carpenter.
The context of COL 69 doesn’t even mention “sinlessness.” It is an exposition on the parable found in Mark 4:2-29 that says, “first the blade, the the ear,” the title of the chapter, in fact. This parable is remarked upon as the illustration of Christian development of the graces of Christ in the believer’s life. Core to this development is the exercise of turning from self and thinking of others and being of help to others as those times present themselves. The quote utilized so often in LGT is not speaking of sinless perfection, but of maturing of the graces of love in the life and practice.
Later in the same book, all the way back on page 384, in the chapter entitled “Who Is My Neighbor?” EGW writes, “Love is the basis of godliness. Whatever the profession, no man has pure love to God unless he has unselfish love for his brother. But we can never come into possession of this spirit by TRYING to love others. What is needed is the love of Christ in the heart. When self is merged in Christ, love springs forth spontaneously. The completeness of Christian character is attained when the impulse to help and bless others springs constantly from within—when the sunshine of heaven fills the heart and is revealed in the countenance.” Note: not one statement of sinlessness, or sinless perfection. Not one iota of “we can do it.” It is our growth in Christ dwelling in us that brings about “character” which is not to be equated with sinlessness.