The advantages enjoyed by men of that age [pre-Flood] to gain a knowledge of God through His works have never been equaled since. And so far from being an era of religious darkness, that was an age of great light. All the world had opportunity to receive instruction from Adam, and those who feared the Lord had also Christ and angels for their teachers.—Patriarchs and Prophets, 83. TA 65.2
Men lived nearly a thousand years in those days [before the Flood], and angels visited them with instruction directly from Christ.—Selected Messages 1:230. TA 65.3