Rather than attempting to argue against pantheism, perhaps the argument for Christ based on Reasonable Wisdom:
Please consider the following:
Each one of us wants happiness on some level, and in order to have happiness there must first be peace.
In order to have peace, there must be patience, for the instance there is impatience, there is a loss of peace.
In order to have happiness, there must be kindness, for the instance there is a lack of kindness, although there may be peace, there is no happiness.
Therefore if a person wants to live in a society of unbreakable peace and limitless happiness for everyone, s/he must help her/himself and others strive to perfect patience and kindness.
This can be gracefully and wisely stated as: "The Greatest...is Love."
And the depths of unconditional patience and kindness (Greatest Love), even in the face of unjust impatience and meanness, is first demonstrated by Jesus Christ in His Crucifixion.
This was enough for me, however, if it is not enough for your friend, as one dives deeper into mastering patience and kindness: the brilliance of the Greatest Commandments is revealed, along with the order of the Beatitudes and the Sacraments, as well as the Catechisms of the Catholic Church.