It Is God Who Justifies

"We've been declared righteous through the Lord Jesus Christ. But so many of us don't live that way because we don't know what it means. Paul speaks to this in Romans 8 ... "Therefore, there is now no condemnation for those who are in Christ Jesus, because through Christ Jesus the law of the Spirit who gives life has set you free from the law of sin and death." "What, then, shall we say in response to these things? If God is for us, who can be against us?" * Why did Adam and Eve sin? Didn't God know they would do that? * Why did the demons want to be in the pigs? And why did they run off the cliff? * What does chasten mean? * How did the serpent get into the Garden of Eden since it was perfect?