The Bible teaches that God knows (Ps 139:2) and judges (Heb 4:12) our thoughts.  One of the great prayers of the Bible is this one: “Let the words of my mouth and the meditation of my heart be acceptable in Your sight, O LORD, my strength and my Redeemer” Ps 19:14 (NKJV).  Since our thought life is an open book to our Lord, we want Him to be pleased with the thoughts we are embracing.  Some thoughts that are evil and horrifying fly through our minds from previous experiences, and from the Tempter himself,.  Our choice should be to reject those thoughts, so that they do not gain root in us.  The thoughts we should embrace are those meditative conclusions we have reached that make us who we are.