Theosis, Justification, Sanctification ?

Here are 4 sources to check out.

First: Beyond Justification; An Orthodox Perspective
Summary
The Orthodox writer, Valerie Karras, addresses the “Joint Declaration on the Doctrine of Justification by Faith” put out jointly by the Lutherans and the Roman Catholics.

He covers this subject by first clarifying the concepts of Original Guilt, Free Will and Imago Dei (Image of God in Latin) delineating the point of view of the three vested parties – the Catholics, Lutherans, and the Orthodox.

In clarifying these concepts, he introduces St. Augustine’s influence on how we understand original sin and especially differentiates the Orthodox understanding. From here one can see what problems can arise from the two different perspectives.

Then he goes on to talk about Justification, Sanctification, and Deification (theosis or sharing), breaking out this topic into three sections:
• Restoration of the Fallen Humanity – Justification as “sharing” [in the Divinity of God]
• Beyond Justification to Salvation as Deification
• Grace, Faith, Theosis, and the Finns

In the last section involving the Finns, he explained Luther’s own understanding of salvation and how it may be at odds with both the current Lutheran understanding and the mainstream Protestant position.

This is a great article to read especially if you can get pass certain technical terms and nomenclature used. To save you time in googling the terms, here is a GLOSSARY:
Soteriology is the branch of Christian theology that deals with salvation
Sola Scriptura is Latin for solely by the Scriptures
Sola Fide is Latin for solely by faith
Sola Gratia is Latin for solely by grace
Traducianism is a doctrine about the origin of the soul (or synonymously, "spirit") in the biblical use of the word about the immaterial aspect of human beings (Genesis 35:18, Matthew 10:28). This immaterial aspect is transmitted through natural generation along with the body, the material aspect of human beings. Traducianism specifically means an individual's soul is derived from the souls of the individual's parents.
Concupiscence is selfish human desire for an object, person, or experience. It is derived from the Latin word concupiscentia, meaning "an intense desire".
Pneumatology in Christian theology refers to the study of the Holy Spirit.
Pelagianism is the heresy that original sin did not taint human nature and that mortal will is still capable of choosing good or evil without Divine aid.
Theanthropos is a person who is worshipped as a god.
Actual Document: Beyond Justification: An Orthodox Perspective

Second: 16th Century Lutheran and Orthodox Exchange
Summary
Set in the geopolitical climate of the time, this paper provides a glimpse of the actual dialogue that transpired between the Lutherans and the Orthodox Church when the Lutherans pulled away from the Roman Catholic Church. The fledgling Lutherans tried to seek theological backing from the Eastern Orthodox Church for their effort in separating from the Roman Church. The paper showed how the conversation ended but projected an optimistic future for further dialogue that have extended to our present time and possible unification discussions into the future.
What are also useful here are the points of doctrinal agreement and the points of doctrinal disagreement.
Actual Document: 16th Century Lutheran and Orthodox Exchange

Third: Justification (Theology)
Summary
Wikipedia definition of justification in Christian theology is God's act of declaring or making a sinner righteous before God.
This link is worth a good look. There is a tabulation of how the various Christian denominations such as the Roman Catholics, Lutheran, Methodist, Orthodox, Reformed stand with respect to the attributes: Process or Event, Type of Action, Permanence, Justification & Sanctification.
Actual Document: Justification (Theology)

Fourth: Salvation – Roman Catholic versus Orthodox Protestant View
Summary
The writer of this essay is Douglas Ernest Woolley. He received Christ in 1980 within the Lutheran Church. He was baptized in water and later in the Holy Spirit in a Non-Denominational Charismatic church between the years 1984 and 1993. He became an adherent of the Assemblies of God Church since 1993. While working as a Systems Engineer in Verizon, he is also a degreed Bible scholar working towards his master’s degree.
Doug’s essay outlines the difference in understanding of salvation between a Roman Catholic and a typical Protestant. This is a interesting and short read.
Actual Document: Salvation - Roman Catholic versus Orthodox Protestant View