All too often people mistake the death and resurrection of Christ to be an excuse for complacency--remaining satisfied where they are because Christ paid the price.
This teaching is 100% false and the Bible tells us this over and over again. It is because Christ died that we should be compelled to action. Grace equips us for good works, it doesn't exempt us from them.
We Are Servants of Christ
There seems to always be a debate going on (whether with ourselves or with others) about grace versus works. There is no "grace versus works". They are mutually exclusive. In other words, if you remove one, faith is incomplete. In fact, not only is it incomplete, it's dead (James 2:26).
Your works confirm your faith. Your faith confirms your works. When we are serious about our gift of salvation and the sacrifice it requires, we see that our lives were meant to be dedicated in service to Christ. (Romans 7:25, 1 Corinthians 7:22).
We are not free from the Law, rather Christ fulfilled what we could not. We are still called to follow it. He didn't abolish it. But we do it through the power of the Holy Spirit. (Matthew 5:17)
We Are Called to Strive
Christians constantly reject Christianity as having "rules" and call it legalism. This is simply not true. The Bible is full of guidelines (aka rules) to follow in order to live a righteous life and confirm your salvation or faith in the work of the cross.
We don't strive to earn God's love. We already have it. We strive to work out our salvation. Is grace a free gift? Not necessarily. It's freely given, but it will cost you your life.
I press toward the goal for the prize of the upward call of God in Christ Jesus. Philippians 3:14
"Upward" in this verse refers to a higher position. God has called us to be more than we are. And He cannot work in us if we stand still.
Legalism Versus Works
So what's the difference between legalism and works?
It's really quite simple. Legalism is man making up rules and teaching them as righteous living.
For example, the kind of food we eat. We are free to eat what we want. There is no law against such living. (Colossians 2:20-23). There are consequences to the kind of food we eat, but it is not considered an eternal matter, therefore to teach others it is a sin to eat poorly is legalism.
God calls us to focus on eternal matters or things above. (Colossians 3:2)
The only way to know how He wants us to live is to pray and read His word. The only way to walk out our faith is to take the steps to live how He has called us to live.
Jesus plainly said, "If you love me, you'll obey my commandments." (John 14:15)
We need to show the Lord we love Him. Furthermore, we need to show our children we love Him.