"Therefore, if anyone is  in Christ, he is a new creation, old  things at intervals are being rendered void; behold, all things have already completely become new" (II Cor. 5:17, Expanded Greek Translation - EGT).

It has proved exciting and rewarding to translate the New Testament from the Greek over the last 20 plus years.  Exact noun definitions and added verbal Greek meanings, bring extra clarity to help us know more of Him.  Greek merely confirms what the Holy Spirit teaches us by His Spirit.  This verse discusses, that at the Spirit new birthing, that all things have completely become new.  The Word confirms that we have the Person (Gal. 2:20), Spirit (Rom. 8:9), nature (II Pet. 1:4), and life of Christ (I John 5:11-12), all from the incorruptible Seed that we received (I Pet. 1:23).  We now are a new creation shared life in Christ.  We are a new breed and race of people.  We are no longer tied to the lineage of Adam.  Adam's lineage was put to death in Christ on the cross.  Our heritage is now tied to Christ as the head of this new creation race of people.  Our lineage in this new creation race is now tied only to Christ, chosen in Him before the foundation of the world (Eph. 1:4).

Most versions (II Cor. 5:17a), indicate that old things are passed away, using the past tense indicating all action is completed.  In context with the prior verse 16, Paul is discussing mind renewal knowing, and carries this into the first half of verse 17.  While all things have already completely become new in Spirit, the old things of the mind are at intervals passing away.  In clearer terms the Greek specifically states, "at intervals are being rendered void" (II Cor. 5:17a), when the Holy Spirit at intervals transforms and renews the mind (Rom. 12:2).  The Holy Spirit's mind renewal process renders void the old stinking thinking and fleshly thinking of and about the past.