"Satan's lying charges against the divine character and government appeared in their true light. He had accused God of seeking merely the exaltation of Himself in requiring submission and obedience from His creatures, and had declared that, while the Creator exacted self-denial from all others, He Himself practiced no self-denial and made no sacrifice. Now it was seen that for the salvation of a fallen and sinful race, the Ruler of the universe had made the greatest sacrifice which love could make; for “God was in Christ, reconciling the world unto Himself.” 2 Corinthians 5:19 . It was seen, also, that while Lucifer had opened the door for the entrance of sin by his desire for honor and supremacy, Christ had, in order to destroy sin, humbled Himself and become obedient unto death. GC 502.2"
"To wit, that God was in Christ, reconciling the world unto himself, not imputing their trespasses unto them; and hath committed unto us the word of reconciliation."
Ellen White directly references 2 Corinthians 5:19 in this passage.
"God had manifested His abhorrence of the principles of rebellion. All heaven saw His justice revealed, both in the condemnation of Satan and in the redemption of man. Lucifer had declared that if the law of God was changeless, and its penalty could not be remitted, every transgressor must be forever debarred from the Creator's favor. He had claimed that the sinful race were placed beyond redemption and were therefore his rightful prey. But the death of Christ was an argument in man's behalf that could not be overthrown. The penalty of the law fell upon Him who was equal with God, and man was free to accept the righteousness of Christ and by a life of penitence and humiliation to triumph, as the Son of God had triumphed, over the power of Satan. Thus God is just and yet the justifier of all who believe in Jesus. GC 502.3"
"Whom God hath set forth to be a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God;"
The EGW passage discusses God's justice and justification of believers through Christ's sacrifice, which aligns with the theme of Romans 3:25 regarding propitiation and the declaration of God's righteousness.