Thank you for asking a question on www.thisisyourbible.com
Actually, there is no such passage in the Bible. The closest is in Genesis 6:1-4. What this means is that the people of God did not remain separate from the evil people of the world and entered into marriages with them. That inevitably led to a breakdown of the community of the faithful until, in a very short time, immorality and violence and corruption filled the earth. The only righteous people left were Noah and his family.
The people of God, known in the Bible as "the sons of God" (see Genesis 4:26 margin; John 1:12; Romans 8:14; Philippians 2:15; 1 John 3:1,2)
I hope you have found this helpful.