"As the worshipers of the true and living God we should bear fruit corresponding to the light and privileges we enjoy. Many are worshiping idols instead of the Lord of heaven and earth. Anything that men love and trust in instead of loving the Lord and trusting wholly in Him becomes an idol and is thus registered in the books of heaven. Even blessings are often turned into a curse. The sympathies of the human heart, strengthened by exercise, are sometimes perverted until they become a snare. If one is reproved, there are always some who will sympathize with him. They entirely overlook the harm that has been done to God's cause by the wrong influence of one whose life and character do not in any way resemble those of the Pattern. God sends His servants with a message to the people professing to be followers of Christ; but some are children of God only in name, and they reject the warning. 5T 250.1"
"Wherefore by their fruits ye shall know them."
Both passages connect actions/behavior with being indicative of one's true allegiance or nature. EGW expands on the idea of 'fruit' to include worshiping idols.
"God has in a wonderful manner endowed man with reasoning powers. He who fitted the tree to bear its burden of goodly fruit has made man capable of bearing the precious fruits of righteousness. He has planted man in His garden and tenderly cared for him, and He expects him to bear fruit. In the parable of the fig tree Christ says: “Behold, these three years I come seeking fruit.” For more than two years has the Owner looked for the fruit that He has a right to expect from these conferences, but how has His search been rewarded? How anxiously we watch a favorite tree or plant, expecting it to reward our care by producing buds, blossoms, and fruit; and how disappointed we are to find upon it nothing but leaves. With how much more anxiety and tender interest does the heavenly Father watch the spiritual growth of those whom He has made in His own image and for whom He condescended to give His Son that they may be elevated, ennobled, and glorified. 5T 250.2"
"He spake also this parable; A certain man had a fig tree planted in his vineyard; and he came and sought fruit thereon, and found none. Then said he unto the dresser of his vineyard, Behold, these three years I come seeking fruit on this fig tree, and find none: cut it down; why cumbereth it the ground? And he answering said unto him, Lord, let it alone this year also, till I shall dig about it, and dung it: And if it bear fruit, well: and if not, then after that thou shalt cut it down."
EGW directly references and expands upon the parable of the fig tree in Luke, drawing parallels between the owner's expectation of fruit from the tree and God's expectation of righteousness from humanity.