Be warned, be encouraged.  Which shall it be?
Make every effort to live in peace with everyone and to be holy; without holiness no one will see the Lord. See to it that no one falls short of the grace of God and that no bitter root grows up to cause trouble and defile many. See that no one is sexually immoral, or is godless like Esau, who for a single meal sold his inheritance rights as the oldest son. Afterward, as you know, when he wanted to inherit this blessing, he was rejected. Even though he sought the blessing with tears, he could not change what he had done.
Hebrews 12:14-17 (NIV)