Rev Timothy Davis, from Christ Church Abingdon, is said to have breached safeguarding procedures through an "intense" mentoring programme with the school boy who's not been identified.
A tribunal, held at Southwark Cathedral, found that the frequency of contact between the vicar and the teenager had grown to inappropriate levels including contact via telephone.
It also heard how mentoring sessions were held in the teenager's bedroom with the door closed - however no misconduct of a sexual nature was reported.
Davis was also found to have overused scripture in conversations with the teenager.
The guilty verdict on spiritual abuse is said to be the first of its kind.
A decision will now be made in regards to suitable punishment.
In a statement to Premier, the Diocese of Oxford said: "Abuse of spiritual authority and power falls far short of the obligations and duties of those in Holy Orders. Clergy are in a privileged position of trust in their congregations and communities. The professional guidelines to which they are bound make clear that this is a trust that they must not abuse.
"The findings of the tribunal show that, sadly, Tim Davis betrayed the trust of everyone involved in a youth mentoring program at Christ Church Abingdon. None more so than the young man and his family who offered their home and hospitality to him.
"The behaviour and actions of Tim Davis during this period are in no way reflective of acceptable church practice. We fully support the findings of the tribunal and now await their decision as to the penalty to be imposed."
A new report, released over the weekend, commissioned by the Churches Child Protection Advisory Service warned spiritual abuse was on the increase with a greater need for understanding on the issue.