This book is exactly what you would expect from an Owen scholar writing on John Owen. It is clear and rarely goes off rabbit-trails. While it is old in some ways, and not every locus of systematic theology gets treated, a careful study of this work will repay pastoral ministry.
Ferguson begins with Owen’s covenant theology. It seems, surprisingly, that Owen held to something like a “works-principle” in Sinai. Covenant of Sinai: sometimes referred to as Old Covenant. Owen is aware of the tensions in saying that all covenants are administrations of the Covenant of Grace. Under the covenant of grace, yet in some way there were principles of the Covenant of Works (JO: 19:389). Sinai can’t simply be Covenant of Grace because of the sharp contrasts between “a better covenant.”
Covenant theology allows Ferguson to draw several inferences on soteriology: Union with Christ: the work of grace–”same instant wherein anyone is united unto Christ, and by the same act whereby he is so united, he is really and habitually purified and sanctified” (JO: 3.517). Effectual calling takes place in Christ, is an act of God the Father (JO: 20: 498), and binds the believer by the indwelling of the spirit (JO: 21:147). Effectual calling produces a change in both status (justification) and life (sanctification), yet it does not identity the two.
Sanctification is the pinnacle of this volume. Structure of sanctification. The work of grace produces the exercise of duty (Ferguson 55). Owen gives a long definition in JO 3.369-370. In one sense it is an immediate work on believers, since it flows from regeneration and from our Head, yet it is also a process (56). The Lord Jesus is the Head from whom all gifts flow, yet the Spirit is the efficient cause who communicates them to us (Ferguson 58).
Very thorough chapter on Assurance and why the believer may experience varying degrees of it. This lets Owen talk about the sealing of the Holy Spirit. Owen: “No special act of the Spirit, but only in an especial effect of his communication unto us” (JO 4:400). He seals the believer by his personal indwelling, but there are no rules as to how/when the believer may recognize it.
With the volumes numerous quotations from Owen, from almost all of his works, we recommend this as a handy guidebook to navigating Owen.