They were in Christ before the foundation by election, but the legal reconciliation for them is when He died, cant you read ? According to Rom 5:10 how were they reconciled to God ?
10 ;For if, when we were enemies, we were reconciled to God by the death of his Son, much more, being reconciled, we shall be saved by his life.
That is a common belief, but incorrect. It was Jesus Who was elect from the foundations of the world. We become elect with Him when we are placed into Him. One thing is unmistakable, and that is that we are elect 'in Him', or "in Christ" per Ephesians chapter one, which says the same over and over. The only other option that you have is that we are 'in Him' from the foundations of the world and already saved, which is what some do to solve that problem, but that's not Biblical, obviously. Read Ephesians 1, you'll see. Elect "in Him, elect "in Christ". It's called corporate election, and that I believe is Biblical. Believe and be saved, the Gospel message is in harmony with that. The message by some today, that is 'be saved and believe' is hostile to the Bible and the simple Gospel message. We receive the life, the Holy Spirit as a result of believing. That places us in Him, and Him in us.
This is how they, all OT believers, were reconciled to God.
Romans 3:25-26 whom God set forth as a propitiation by His blood, through faith, to demonstrate His righteousness, because in His forbearance God had passed over the sins that were previously committed (not reconciled), to demonstrate at the present time His righteousness, that He might be just and the justifier of the one who has faith in Jesus (reconciled).
Nobody is reconciled until they are placed into Christ Jesus. No OT believer was placed into Christ until after the death, resurrection and ascension. No believer can become the Temple of the Holy Spirit (NT only) without blood to cleanse that Temple. We cannot be placed into Christ without that indwelling, which spiritually baptizes/places us into Christ. The Agent of that placing into, the Holy Spirit indwelling, the death and resurrection and ascension, all waited for each other and were all needed for believers to be reconciled.
Jesus is the Church, the One True Church. Everyone believes that the Church was birthed at Pentecost, but most never ask what that means? The first placed into Christ and saved , both practically and legally. That's how it was birthed.
This is what John prophesied about near the end of the OT, and that prophecy went all the way back to Ezekiel. The baptism/placing into with/by the Holy Spirit is what was given at Pentecost. It was owed to some, because they already trusted Jesus. Owed to others true OT believrs who had not yet heard the Gospel, they were predestined to hear and believe, and, as a result, be placed into Christ, reconciled. this is haw it happens.
1 Corinthians 12:13 For by one Spirit we were all baptized into one body--whether Jews or Greeks, whether slaves or free--and have all been made to drink into one Spirit.
Dave