Ten Minas offers a free group Bible study on Christian Atonement.
Below are links to the Bible study itself (in PDF format) along with a
Teacher's Edition (i.e., a version with the answers). This study is
designed to be undertaken by a group, with the floor open for
discussion of the various questions. But if you want to go through the
study yourself, that is possible. Just read the Bible passages and
answer the questions in the student edition first, then check your
answers against what is in the Teacher's Edition.