Is the Gospel opposed to the law of God. Many Christians believe that the Gospel exempts a person from having to obey the law of God. But Jesus says this- 

Matthew 13:39-43 "The harvest is the end of the age, and the reapers are angels. 40 Just as the weeds are gathered and burned with fire, so will it be at the end of the age. 41 The Son of Man will send his angels, and they will gather out of his kingdom all causes of sin and all law-breakers, 42 and throw them into the fiery furnace. In that place there will be weeping and gnashing of teeth. 43 Then the righteous will shine like the sun in the kingdom of their Father. He who has ears, let him hear."   ESV

Read this study to find out why a person who is saved by Grace will obey the law of God.