I'm only now able to delve into this conversation for alas I finally read about Origen in the current book I am reading entitled, "Getting to Know the Church Fathers: An Evangelical Introduction" by Bryan M. Litfin.
Origen was indeed a neo-Platonist, primarily because he was schooled in Alexandria, Egypt where higher learning was advocated, including philosophy. Plato sought to bridge the gap between a "higher-plane" of reasoning with the physical world that we live. And Origen was instrumental in bridging that gap by explaining how Jesus Christ was sent from above down to earth and reconciled man to God. As a result, many philosophical thinkers of Origen's day were brought into a relationship with Christ.
What Origen brought to the table was a high emphasis on spiritual allegory. As a result, Origen was able to clearly articulate how many elements contained within the Old Testament point to Jesus Christ, something that nobody else had been able to do in the early church years. Many of these truths are still taught and adhered to today by many Christians. In fact, C.S. Lewis gleaned a lot from Origen's writings because he sought the value in telling allegorical stories with a higher spiritual message involved. Case in point, "The Chronicles of Narnia" was an allegorical tale about a risen lion king resembling the great lion of Judah and King of Kings, Jesus Christ.
To be fair, Origen did indeed have some unorthodox beliefs especially concerning the trinity. However, the doctrine of the trinity had not been firmly established by this point yet. It was still in discovery mode. It wasn't until Athanasius cleared up this matter in the early 4th century AD, nearly 50-60 years after Origen. And, with his philosophical bent, Origen sometimes failed to capture the true essence of the Christian faith. But, in modern terms, Origen was "culturally relevant" for his day.
Even though Origen had some flaws (don't we all?), fundamentally Origen was a true believer of Jesus Christ. How do I know this? Let the words of Origen himself best describe how he wished to be remembered as upon his death:
"As for myself, my wish is to be truly a man of the church, to be called by the name of Christ and not of any heretic, to have his name which is blessed all over the earth; I desire to be, and to be called, a Christian, in my works as in my thoughts." (A quotation from Origen's Commentary on Luke; Origen: On First Principles, xiii)