Romans 8:28 is one of those verses in Scripture that Believers hold fast to:
“And we know that all things work together for good to those who love God, to those who are the called according to His purpose.”  
 
God’s purpose, the plan of salvation unto eternal life with Him.  It did not start in the New Testament.  Let’s see what Scripture tells us (of course, the whole of Scripture is about His plan.  Hopefully, it will draw you into a daily study of the Word.)  
 
The first recorded promise (God speaking to the serpent at the fall):
“And I will put enmity 
Between you and the woman,
And between your seed and her Seed’
He shall bruise your head,
And you shall bruise His heel.”  Genesis 3:15
 
The purpose is announced by counsel and foreknowledge:
“Men of Israel hear these words: Jesus of Nazareth, a Man attested by God to you by miracles, wonders, and signs which God did through Him in your midst, as you yourselves also know--
Him, being delivered by the determined counsel and foreknowledge of God, you have taken by lawless hand, have crucified and put to death.”  Acts 2:22-23
 
Based upon the foreknowledge of God:
“For whom He foreknew, He also predestined to be conformed to the image of His Son, that He might be the firstborn among many brethren.”  Romans 8:29
 
The heavenly wisdom of His plan:
“But we speak the wisdom of God in a mystery, the hidden wisdom which God ordained before the ages for our glory, which none of the rulers of this age knew; for had they known they would not have crucified the Lord of glory.  1 Corinthians 2:7-8
 
It was God’s good pleasure:
“Just as He chose us in Him before the foundation of the world, that we should be holy and without blame before Him in love, having predestined us to adoption as sons by Jesus Christ to Himself, according to the good pleasure of His will.”  Ephesians 1:4-5
 
For those ordained:
“For so the Lord has commanded us:
‘I have set you to be a light to the Gentiles,
  That you should be for salvation to the ends of the earth.’”  Acts 13:47
Vs. 48 goes on to say,
“Now when the Gentiles heard this, they were glad and glorified the word of the Lord.  And as many as had been appointed to eternal life believed.”
 
God’s is an unchanging purpose:
“(God) who has saved us and called us with a holy calling, not according to our works, but according to His own purpose and grace which was given to us in Christ Jesus before time began.”  2 Timothy 1:9
 
Planned before creation;
The opening of Paul’s letter to Titus,
“Paul, a servant of God and an apostle of Jesus Christ, according to the faith of God’s elect and the acknowledgment of the truth which is according to godliness, in hope of eternal life which God, who cannot lie, promised before time began.  Titus 1:1-2
 
Provided for the sanctification of Believers:
“Who were chosen and foreknown by God the Father and consecrated (sanctified, made holy) by the Spirit to be obedient to Jesus Christ (the Messiah) and to be sprinkled with [His] blood…”  1 Peter 1:2
 
At the beginning centered in the death of Jesus Christ:
Revelation 13:8,
“the Lamb (Jesus Christ) slain from the foundation of the world.”
 
Holy God, we are in awe that in the counsel of eternity past, before time began, You purposed and planned the way of salvation to all who would believe!
How awesomely gracious, loving, merciful and wonderful are You!  In truth, there are no words to describe Your magnificence!  We love and adore You most precious God: Father, Jesus and Holy Spirit.  With grateful hearts we thank you!  Amen