The mortal death of Jesus, according to Paul, is an historical interpretation we know well. Paul's interpretations were developed from very immediate, sincere, personal, cultural, and educated perspectives. The Old Testament concepts of God used by Paul restricted his interpretation of the events of Jesus' life and death. Paul's interpretation was appropriate in light of his cultural heritage, religious indoctrination, and education, and from the revelation he received on the way to Damascus.
For Paul, what else could the death of Jesus be than a sacrifice that appeased God and atoned for the sins of all mankind? In his time, the death of Jesus as a sacrifice was a reasonably obvious conclusion. All these factors led him to interpret the death of Jesus as he did. Most anyone at that time would have come to the same conclusion.
The effect of Paul's interpretation was an immediate healing for Jesus' followers and new believers. Though the violent murder of Jesus aroused self-hatred in believers for their associated involvement in the crime, Paul's interpretation reconciled this horrific event. His interpretation provided a new paradigm for belief that has lasted two millennia. No small feat at all! It provided Jesus' followers with a belief and faith that transcended the death of Jesus and the Apostles, and prevented the fragmentation of the early Christian movement. Paul's interpretation of Jesus' death was needed then to affirm and assure believers their relationship with God was at peace— that the tearing of the God-individual relationship was reconciled.
