Why bother with the Law?

Christians are saved by grace--meaning we are accepted by God already based on the work of Jesus. It is not like all other religions where we have to abide by certain creeds or do good works in order to be accepted by God. 

So, why should Christians do any good work or obey God's commandments? And why would God create such a salvation plan, is it not too easy for us to abuse his grace? 

I think the answer lies in how seriously we believe in Jesus in the first place. If we truly believe that God squeezed himself into a human body, endured abuse, mockery, and death in the greatest measure in order to save us. Would this not make us love him? And when we love someone, don't we want to do what pleases that person. In the Bible, we are told again and again that our obedience makes God happy. 

In Exodus 19:5-6, God said to the Israelites--after he had delivered them out of slavery in Egypt--that if they obey him fully and keep his covenant with them, then they will be his 'treasured possession' amongst all the nations. And it is the same for Christians as indicated in John 15:10 "If you obey my commands, you will remain in my love, just as I have obeyed my Father's commands and remain in his love". Who wouldn't want to be God's treasured possession and remain in his love?