God has lovingly accepted us, so we are free to be motivated to do good works. But the sinful flesh within us is in conflict with the Spirit of God at work in us. Further, the law brings its own challenge: we strain against the law and break it.
We need to add our will to the Spirit’s leading, so that we voluntarily yield to God’s perfect path for our lives. We need to ensure that we are worshipping God, not idols, not anything or anyone that will turn our hearts away from God.
The law can’t bring life or fruitfulness: Legalism is barren. So if the church goes back to the slavery of the law it will mean barrenness and disobedience to the word of God. It is only by grace that the church can be fruitful and spread across the world.