We don't know much about the historic Jesus but vestiges of his historical life can be looked through on the synoptic evangiles of Marc, Mathews and Luc. While Marc evangile is the main source for Mathew and Luc, the exegetes find that Mathew and Luc had at disposition another literary source, the "Q" (source), while Luc still disposed of other elements not known to the other two synoptic evangelists. The main reason for Jesus activity may be found on his announcement of the "Kingdom of God" (KG). As announced in the beginning of the first evangile to be written, that of Marc: After John had been arrested, Jesus came into Galilee proclaiming the Gospel of God: "The time has come; the Kingdom of God is upon you; repent and believe the Gospel." (Mark, 1, 14-15). This is probably the most old message of the historic Jesus, the one that summarises the objective of his predication and life. What was for Jesus the KG? That the time was completed and God himself was coming to instal His justice to end the corruption of those that had reigned in His name with devastating consequences for the poorest and weakest of the land, by subjugating these with thousands of the law precepts while they lived in luxury on palaces. In one word as Jesus called them repeatedly, those that were supposed to represent Him: hypocrites. Therefore the message of Jesus was clear, a message against the masters of the land, the powerful, and in favour of the poor and the simple. This was his Theology but how can it be turned into an Ecotheology? By assuming that the poorest and simple of the land on the time of Jesus are now being oppressed by the additional consequence of the powerful and greedy with the possibility of hypocrisy (M.Henry: Paroles du Christ, p.24, Éd. du Seuil, 2002) that is the enormous impact of the environmental devastation and climatic change. The invitation to the KG continues: an interreligious approach on eco-justice will bring the KG with repent and believe on the Gospel.