There is obedience and there is legalism.
Legalism is following rituals and formulas of behavior, a prime example of this is Catholicism.
Obedience is just that obeying, but what is there to obey? The Bible sets out a certain type of lifestyle that we are to live. This lifestyle is not legalistic it is as I already said, obedience. This is something that should be something you desire to do if you truly follow Christ for they are His own teachings.
He came here to fulfill the rules of obedience not to replace them, so if any says you do not have to follow the teaching of the Bible just because you have received the grace of God’s salvation through His Son the Lord Jesus Christ, then they have either lied to you or have no true understanding of the Bible and its teachings.
You cannot live in sin and say you are a “Christian” period. Sure we all sin, but those that try to avoid it and feel remorse when they do it are striving to be obedient to God. Those that live in sin and care only for their own desires and happiness are disobedient. It is that simple.