Know the truth=be free
John 8:31-32 Then said Jesus to those Jews which believed on Him, If ye abide in my word, then are ye my disciples indeed, and ye shall know the truth, and the truth shall make you free.
If the Son therefore shall make you free, ye shall be free indeed.
children OF GOD=glorious freedom
...creation itself will be liberated from its bondage to decay and brought into the glorious freedom of the children of God.