If you are a Christian then why do you have evil thoughts?

Even though we are saved and try to do God’s will in our life, we are constantly bombarded with evil.  The reason for this is because our bodies still have the sin nature in them.  While our soul is saved and tries to follow God, our flesh still wants and desires sin and evil (Romans 7:21-23).  Our thoughts should be pure, and we should strive for this on a daily basis (Philippians 4:8).  However, since we are not sinless while on this earth our flesh drives us towards wickedness (Romans 7:18).  This is why we need to count ourselves as dead to sin every day and offer ourselves to the service of our Lord and Savior Jesus Christ (Romans 12:1-2).