In his introduction to Walter Marshall's classic on sanctification, The Gospel Mystery of Sanctification, Joel Beeke has some helpful; commentary on the book. Here are a few quotes I collected from the book's intro:
To believe on Christ rightly means to receive the proof of the Gospel and to come to the Christ of the gospel. To come to Christ rightly means to receive him as a free gift with ardent affection, trusting in him alone for salvation. Joel Beeke on Howard Marshall's beliefs.
... Where there is little difference between a Christian and non-Christian in what we think and believe, there will soon be little difference in how we live.
As long as Christ remains outside of us, all that He has suffered for the salvation of sinners is meaningless to us.