Paul D. Molnar.  Faith, Freedom and the Spirit: The Economic Trinity in Barth, Torrance and Contemporary Theology.  Downers Grove, Illinois: IVP Academic, 2015.  See here for Intervarsity Press’s page about the book.
Paul D. Molnar teaches Systematic Theology at St. John’s University, which is located in Queens, New York.  Faith, Freedom and the Spirit seems to build on an earlier book that Molnar wrote, Divine Freedom and the Doctrine of the Immanent Trinity: In Dialogue with Karl Barth and Contemporary Theology (New York: T&T Clark, 2002).  Molnar also responds to certain critiques of that work.
I had heard the terms “economic Trinity” and “imminent Trinity” 
before, and I had a vague idea what they meant.  A theology student told
 me years ago that God the Son (who became Jesus Christ) is equal to God
 the Father in terms of his nature and power, yet submits himself in 
obedience to the Father in terms of his function, role, and activity.  
The latter, according to this student, is the economic Trinity.  I still
 felt that I should probably look up these terms in order to understand 
Molnar’s book.  Here is what wikipedia says (and
 please don’t chew me out for using wikipedia!): “The economic Trinity 
refers to the acts of the triune God with respect to the creation, 
history, salvation, the formation of the Church, the daily lives of 
believers, etc. and describes how the Trinity operates within history in
 terms of the roles or functions performed by each Person of the 
Trinity—God’s relationship with creation. The ontological (or essential 
or immanent) Trinity speaks of the interior life of the Trinity—the 
reciprocal relationships of Father, Son, and Spirit to each other 
without reference to God’s relationship with creation.”
How exactly does this relate to Molnar’s Faith, Freedom and the Spirit? 
 The economic Trinity describes the roles that the Father, the Son, and 
the Holy Spirit perform in their relationship with creation, especially 
humanity.  God the Son as Jesus, for example, submits himself to the 
Father’s will and dies for our sins, and so Jesus fulfills a role as 
redeemer in his relationship with certain human beings.  The Holy Spirit
 indwells believers.  The immanent Trinity, however, concerns the 
relationship of the Father, the Son, and the Holy Spirit with each 
other, apart from their roles in relating to creation.  The Father, the 
Son, and the Holy Spirit existed eternally, long before creation, in a 
relationship of love.
According to Molnar, there are theologians who are trying to collapse
 the economic Trinity into the immanent Trinity, and they are saying 
that the influential twentieth century theologian Karl Barth actually 
came to do the same thing in the course of his thought.  One view is 
that God the Son was always incarnate, even before Jesus was born.  
After all, one can argue, there is no before or after with God, since 
God is eternal and outside of time, so can we legitimately say that God 
the Son was fleshless, then became a human being in the first century 
and learned about human suffering so he could relate to us better, then 
went back to heaven with resurrected flesh, and the insights that he 
gained from the incarnation?  No, some seem to say: there is no before 
or after with God, so God the Son was always incarnate, always carrying 
that knowledge of what it means to suffer!  Another view is that God 
somehow decided to fashion the Trinity because God was planning to 
relate to human beings as a Trinity: as Father, as Son, and as Holy 
Spirit.  The Trinity, according to this view, does not seem to be 
something that God intrinsically is and always has been, but rather is 
something that God decided to become in light of how he would relate to 
his creation.
Molnar emphatically disagrees with these views, and he argues 
extensively that they are not faithful to what Karl Barth actually 
taught.  Molnar does believe that Karl Barth went off the right path, in
 some instances.  Barth seemed to imply that God the Son becoming a 
human being was inevitable, which arguably undercuts God the Son’s 
freedom by saying that he had to do something.  According to 
Molnar, Barth also occasionally leaned in the direction of treating God 
the Son as naturally inferior to God the Father, rather than as equal 
with God the Father in his nature.  Still, Molnar does not think that 
Barth went as far as some theologians think, and he maintains that, in 
many respects, Barth is consistent with the Bible and the overall stream
 of historical orthodox Christian theology.
Molnar also interacts with the views of Barth and theologian Thomas 
Torrance about divine revelation.  Molnar highlights that, for Barth, 
God reveals himself to people through the Gospel and person of Jesus 
Christ, and God through the Holy Spirit convinces them thereby about the
 truth of the Gospel and their need for salvation from sin.  According 
to Molnar, Barth is different from theologians who believe that humans 
can find God through self-acceptance, by listening to their conscience, 
or by looking to nature or philosophy.  No, Barth believes that God must
 reveal himself to sinful human beings through Christ and the Holy 
Spirit for them to know God.
These topics of the nature of the Trinity and divine revelation look 
like two different topics, and one can ask how Molnar believes that they
 intersect with each other.  One can also inquire why Molnar thinks that
 they are important.  Why should I care, for example, whether or not God
 the Son was always incarnate?  Is this debate and the others Molnar 
discusses substantially equivalent to the debate over how many angels 
can dance on the head of the pin, or do they have profound, significant 
ramifications?
Well, one topic that flows through the book is that of freedom: God’s
 and ours.  Molnar seems to argue that God has freedom in the sense that
 God chose to redeem human beings.  God did not have to do so, and his 
plan to do so had nothing to do with how he instrinsically is in the 
Trinity.  God chose to love us.  I have heard more than one 
preacher say something similar: that God did not love us out of any 
neediness on God’s part, for God was already giving and receiving love 
within the Trinity.  Somehow, in this argument and in the arguments that
 Molnar makes, there is a sense that God cannot be dependent on us, that
 it compromises God’s honor and majesty to say that he is.
Regarding our freedom, Molnar appears to agree with Barth that God by
 revelation frees human beings from their slavery to sin and thus 
inspires them to obey God.  Do these inspired human beings then have the
 freedom to sin?  It is hard to tell from Molnar’s discussion.  On the 
one hand, such a model presumes that the humans receiving divine 
revelation get a new worldview, one that yields them to God.  On the 
other hand, however, Barth acknowledged that even Christians can fall 
into the temptation of trying to dodge the challenges of the Gospel by 
substituting for Jesus their own version of God.
Molnar did try to pull the different pieces of his book together in 
his conclusion, and I do give him credit for his attempt, even if I am 
not entirely clear how they hold together.  Still, I have questions.  
Why can we not say that God had to redeem us?  Perhaps God’s 
love compelled him to do so.  Molnar says in one place that he is open 
to saying that the love that the Son has for the Father is related 
somehow to the love that God the Son has for us (i.e., Christ redeemed 
us out of his love for the Father, or God extends the love that exists 
in the Trinity to us); Molnar says elsewhere in the book, perhaps 
quoting a theologian with whom he seems to agree, that freedom for God 
does not mean that a variety of alternatives are equally on the table 
for God to pursue.  God is righteous and acts righteously.  Maybe love 
is so much a part of who God is that God could not just sit back and let
 humanity fall into oblivion, but God felt compelled to save us.
I also wonder how Barth would address why some human beings appear to
 receive God’s revelation, while others do not, for Barth places a lot 
of emphasis on God’s agency in the revelation and conversion of people, 
while saying that we cannot climb our own way to a knowledge of God.  
Some characterize Barth as a universalist, so perhaps Barth thought 
that, eventually, God would reveal Christ to everyone, who would then be
 inspired to turn to God.
This book was very repetitive, in that it continually repeated 
certain themes.  I do not entirely fault Molnar for this, for he was 
extensively trying to document and to show that certain theologians have
 Barth wrong.  I wish, though, that he spent more space explaining why 
he thought his discussions were so significant.  I will add that the 
book did have an interesting discussion of God’s passivity and 
impassivity.  This is relevant to the issue of Christ’s suffering, for 
an aspect of God is that God does not suffer: God cannot be hurt by 
human beings but is always happy and at peace.  Molnar seems to contend 
that passivity and impassivity are both part of God—-that, yes, Jesus 
suffered, and yet there is a peace that exists within God that God 
imparts to us.
I apologize for any misunderstanding of Molnar on my part!
I received a complementary copy of this book from Intervarsity Press in exchange for an honest review.