Obeying God is not legalism

 If we love God then we obey Him out of a cheerful heart as His comandments are not grievous.

John 14:4, 15 KJV
And whither I go ye know, and the way ye know. [15] If ye love me, keep my commandments.

1 John 5:3 KJV
For this is the love of God, that we keep his commandments: and his commandments are not grievous.

Acts 5:29 KJV
Then Peter and the other apostles answered and said, We ought to obey God rather than men.

Philippians 2:12 KJV
Wherefore, my beloved, as ye have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling.