The fact is that legalism is a sign of unbelief Heb 3:12.
The person who is unable to believe in GraceThroughFaith adds performance to the mix Gal 3:3. Satan sets out to blind such to this question and its answer:
How much performance is enough?
The HolySpirit has willed that we be forgiven Isa 43:25, that we become His children Rom 8:15 so that He becomes our HeavenlyFather Heb 8:10.
We are saved by faith in His will and the perfect, finished work of Christ Jesus along with our confession of this transcending Truth Rom 10:9,10.
The power of a guilt free life is what Satan fears Mat 8:29. A person whose mind and heart is unfettered by self-doubt and introspection is liberated to see the glory of the HolySpirit and to manifest it Joh 14:12.
We are justified by GraceThroughFaith. Living in that justification is the gift of the HolySpirit and our privilege.