⁵ Having predestinated us unto the adoption of children by Jesus Christ to himself, according to the good pleasure of his will, Ephesians 1:5 (KJV)

“Having predestinated (Gr. =proorizo, ‘marked off beforehand’) us unto the adoption of children (Gr. =huiothesia, sonship) by Jesus Christ to Himself, according to the good pleasure of His will,” (Eph 1:5)

The subject of predestination has long been a topic of great controversy and has confused many knowledgeable Bible students. The issue becomes more complicated when we confuse modern day language, laws and customs with the laws and customs of the time these words were written.

What Eph 1:5 does not say is, that we have been ‘predestinated unto salvation.’ This letter of Paul was addressed to “saints who are faithful.” (Eph 1:1) This title is not addressed to those we may think of as ordinary ‘Sunday go to meeting’ Christians, but rather, those who had a special knowledge or enlightenment of God’s purposes. This letter describes “the mystery,” a secret that was hid in God before the ages and was then, at that time, revealed only to the Apostle Paul.

² If ye have heard of the dispensation of the grace of God which is given me to you-ward: ³  How that by revelation he made known unto me [Paul] the mystery; (as I wrote afore in few words, Ephesians 3:2-3 (KJV)
⁷ Whereof I [Paul] was made a minister, according to the gift of the grace of God given unto me by the effectual working of his power. ⁸ Unto me, who am less than the least of all saints, is this grace given, that I should preach among the Gentiles the unsearchable riches of Christ; ⁹  And to make all men see what is the fellowship of the mystery, which from the beginning of the world hath been hid in God, who created all things by Jesus Christ: Ephesians 3:7-9 (KJV)

This secret is vital in God’s purposes for the ages and describes a hope for a portion of God’s family called “the church which is His body” whose hope and destination is associated with heavenly places. This destination is above the heavens where Christ sits on the right hand of God.

³ Blessed be the God and Father of our Lord Jesus Christ, who hath blessed us with all spiritual blessings in heavenly places in Christ: Ephesians 1:3 (KJV)
²⁰ Which he wrought in Christ, when he raised him from the dead, and set him at his own right hand in the heavenly places, Ephesians 1:20 (KJV)

This epistle speaks of the Lord Christ Jesus in His fullest and exalted position, “Far above all principality, and power, and might, and dominion, and every name that is named, not only in this world, but also in that which is to come: And hath put all things under His feet, and gave Him to be the head over all things to the church, which is His body, the fulness of Him that filleth all in all.

²¹ Far above all principality, and power, and might, and dominion, and every name that is named, not only in this world, but also in that which is to come: ²² And hath put all things under his feet, and gave him to be the head over all things to the church, ²³ Which is his body, the fulness of him that filleth all in all. Ephesians 1:21-23 (KJV)

For what purpose are these believers ‘marked off beforehand’?

Not for salvation, rather, they are ‘marked off beforehand’ for sonship (adoption). God, in His foreknowledge, looked off into the horizon of time and marked off some believers, to sonship. There was and is a purpose in mind for this body of believers. Regarding “...the dispensation of the fulness of times He might gather together (head up together) in one all things in Christ, both which are in heaven, and which are on earth; even in Him... (Eph1:10). This goes far beyond the destination of the human realm of this body of believers, but includes principalities, powers, mights and dominions. To limit the meaning of adoption (sonship) to our modern day use of the word adoption, results in confusion and veils the precious truth prescribed in Eph 1:5.

⁵ Having predestinated us unto the adoption of children by Jesus Christ to himself, according to the good pleasure of his will, Ephesians 1:5 (KJV)

Paul uses a word known to the Greek and Roman world of his time to describe the immutable, absolute surety of the position of those who have received the knowledge of the mystery of His will (Eph 1:9 below). The term “sonship” is a legal term that represented an irrevocable contract.

⁹ Having made known unto us the mystery [Gk. musterion, secret] of his will, according to his good pleasure which he hath purposed in himself: Ephesians 1:9 (KJV)

The adopted son became a member of the family, as though he was a blood relation of the adopter. The effect of adoption included: a change of family, a change of name, a change of home and new responsibilities and privileges which included the capacity of inheritance. If these contractual terms can be applied to those mentioned in Eph 1:5 and to us, then the change of family, name, home, and responsibilities and privileges are surely spiritual blessings far beyond our comprehension.

Mildly adapted for emphasis from: http://www.tftmin.org/archive/marked-off-beforehand-for-sonship