Theosis is having the state of deity and in its strictest definition can only apply to God. However, theologically speaking, theosis also speaks to the partaking of the "divine nature" as Peter puts it in this passage from 2 Peter 1:3–5: "His divine power has granted to us all things that pertain to life and godliness, through the knowledge of him who called us to his own glory and excellence, by which he has granted to us his precious and very great promises, so that through them you may become partakers of the divine nature, having escaped from the corruption that is in the world because of sinful desire."
Theosis – What is it?
Peter writes about the amazing and awesome thing God does for the Christian in making the Christian a part His family. The Bible sometimes calls this sonship, the indwelling of God, or being made associates in His kingdom.
Paul touched upon the idea in Romans 12:2: "Do not be conformed to this world, but be transformed by the renewal of your mind, that by testing you may discern what is the will of God, what is good and acceptable and perfect." To discern, or move toward the will of God, a person must have God working from within. This is theosis.
Theosis is the exhibiting of God in a person and is associated with perichoresis, the Greek term describing the way each Person of the Trinity relates within the Trinity.
Jesus also talked about this transformation when He commanded His followers to be "perfect" in the same way God is perfect (Matthew 5:48). He was saying that His followers should allow the exhibition of God within their lives to such an extent that God shows through. He makes this command during the Sermon on the Mount. Jesus began this sermon with the Beatitudes, which, in part, describe character traits only achievable through the Holy Spirit. Jesus also talks about various aspects of the Old Testament law and makes clear that God desires righteousness hearts, not just righteous actions. Again, something only made possible through God's work in us.
First Peter 1:13–16 says, "Therefore, preparing your minds for action, and being sober-minded, set your hope fully on the grace that will be brought to you at the revelation of Jesus Christ. As obedient children, do not be conformed to the passions of your former ignorance, but as he who called you is holy, you also be holy in all your conduct, since it is written, 'You shall be holy, for I am holy.'" Romans 8:29 says, "For those whom he foreknew he also predestined to be conformed to the image of his Son, in order that he might be the firstborn among many brothers." The Christian's goal is to be holy as God is holy, to be more like Jesus. But this is not a work done in our own strength. Theosis is only possible because of God's work within us.
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What does it mean that a Christian is becoming a new man / woman?
What is growing in faith? How can a Christian grow in faith?
Are believers in Christ little gods?
What is the Trinity?
Truth about Theology