"The human race yet retained much of its early vigor. But a few generations had passed since Adam had access to the tree which was to prolong life; and man's existence was still measured by centuries. Had that long- lived people, with their rare powers to plan and execute, devoted themselves to the service of God, they would have made their Creator's name a praise in the earth, and would have answered the purpose for which He gave them life. But they failed to do this. There were many giants, men of great stature and strength, renowned for wisdom, skillful in devising the most cunning and wonderful works; but their guilt in giving loose rein to iniquity was in proportion to their skill and mental ability. PP 90.2"
"There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown."
The EGW passage directly alludes to the giants mentioned in Genesis 6:4 and expands on their characteristics and impact, making a clear connection.
"God bestowed upon these antediluvians many and rich gifts; but they used His bounties to glorify themselves, and turned them into a curse by fixing their affections upon the gifts instead of the Giver. They employed the gold and silver, the precious stones and the choice wood, in the construction of habitations for themselves, and endeavored to excel one another in beautifying their dwellings with the most skillful workmanship. They sought only to gratify the desires of their own proud hearts, and reveled in scenes of pleasure and wickedness. Not desiring to retain God in their knowledge, they soon came to deny His existence. They adored nature in place of the God of nature. They glorified human genius, worshiped the works of their own hands, and taught their children to bow down to graven images. PP 90.3"
"Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened."
The EGW passage describes the antediluvians' rejection of God in favor of material possessions and self-glorification, mirroring the sentiment in Romans 1:21 about knowing God but not glorifying Him or being thankful. The darkening of their hearts and denial of God's existence in the EGW passage directly reflects the consequence mentioned in Romans 1:21.