Whom God hath set forth. What we see here in Romans 3:25 is the purpose, the reason Jesus Christ, the Son of God, the second member of the Godhead came into creation. Christ Jesus the Son of God was set forth.
Mark 10:45 For even the Son of man came not to be ministered unto, but to minister, and to give his life a ransom for many.
1 Peter 1:19 But with the precious blood of Christ, as of a lamb without blemish and without spot: 20 Who verily was foreordained before the foundation of the world, but was manifest in these last times for you,
Revelation 13:8 And all that dwell upon the earth shall worship him, whose names are not written in the book of life of the Lamb slain from the foundation of the world.
Christ was set forth as the lamb slain. He came to be a ransom. His role was not an afterthought. He was not a solution to the unforeseen problem of sin in the world. He was ordained before the foundation of the world as Peter wrote above. He was set forth for a purpose. That purpose existed, but the carrying out of that purpose and therefore its effects did not exist until He was set forth. Specifically here, that propitiation did not exist until Christ came. This setting forth of Christ manifested the love of God.
1 John 4:9 In this was manifested the love of God toward us, because that God sent his only begotten Son into the world, that we might live through him.
Christ was set forth to manifest the love of God. This setting Him forth to us is the evidence of the love of God toward us. Because of this setting forth we have peace with God. This setting forth of Christ was purposeful, it was not God’s plan B. This was the plan of God. It was the plan of God but it was not carried out until He came.
Ephesians 3:11 According to the eternal purpose which he purposed in Christ Jesus our Lord:
1 Timothy 1:9 Who hath saved us, and called us with an holy calling, not according to our works, but according to his own purpose and grace, which was given us in Christ Jesus before the world began,
The eternal purpose of God was to set forth His Son. The role of Christ in creation was purposed before the world began. God purposed that He would satisfy Himself by setting forth His Son as an offering to Himself.
Isaiah 53:11 He shall see of the travail of his soul, and shall be satisfied: by his knowledge shall my righteous servant justify many; for he shall bear their iniquities.
Ephesians 5:2 And walk in love, as Christ also hath loved us, and hath given himself for us an offering and a sacrifice to God for a sweetsmelling savour.
Look at some of the word in John 7:
John 7:6 Then Jesus said unto them, My time is not yet come: but your time is alway ready.
John 7:30 Then they sought to take him: but no man laid hands on him, because his hour was not yet come.
His time had not yet come. This was the time for which He was set forth. For the new covenant that was to come there had to be a body, there had to be blood to spill.
Romans 5:6 For when we were yet without strength, in due time Christ died for the ungodly.
In due time, at the purposed time, at the ordained time Christ was set forth. This points to our next section of Romans 3:25, the propitiation.