My advice for anyone wanting to understand what Jesus accomplished for every Christian, is not to read some extrabiblical book on how to understand God’s free Grace.
I recommend that anyone prayerfully read in the KJV:

• Romans chapters 3-5
https://av1611.com/kjbp/kjv-bible-text/Ro-3.html

• The book of Galatians
https://av1611.com/kjbp/kjv-bible-text/Ga-1.html

• Hebrews chapters 7-10
https://av1611.com/kjbp/kjv-bible-text/Heb-7.html

That’s the perfect & supreme teaching about God’s free Grace. If you’ll embrace what God teaches there, (and use that scriptural truth as your test for every religious teaching that you encounter), you’ll be set free of religion’s fog forevermore. Your religious shackles will be permanently shattered, you’ll be free in Christ as He intends you to be. (There’s no point in exploring other topics if the Christian isn’t FIRST established in free righteousness).