Grace believers "believe" in the finished work of Christ and we love to confess everything to the Father. We believe that the forgiveness of sins is "the gospel"
This is like saying, the gospel is going up to a sports team after a muddy match, when they are covered in dirt and saying here is a bath to make yourselves clean, and then saying you are clean, and then expecting them to go home without getting washed.
The statement means nothing unless people are actually cleaned and walk in being clean.
Just because your sins are forgiven, does not mean you will not sin again and be in the same mess again.
Of the 10 lepers healed only one came back to find out more about Jesus.
All christians believe in God's grace in sending Jesus to die for us upon the cross for the forgiveness of sins.
Where we differ is what that means and how we apply it to our lives.
I
walk in the way of righteousness, along the paths of justice,
bestowing a rich inheritance on those who love me and making their treasuries full.
Prov 8:19-21
Follow God’s example, therefore, as dearly loved children and
walk in the way of love, just as Christ loved us and gave himself up for us as a fragrant offering and sacrifice to God.
Eph 5:1-2