Twenty years ago, in the Island of Tanna (Vanuatu), the historical opposition between 'man blong skul' (Christian convert) and 'man blong kastom' (custom follower) was still alive, although more complex after a century of Christianization. Whatever the individual denomination of Tannese, the social groups to which they belong are positioned on a syncretistic scale between the 'ful kastom' and 'stret kristian' poles, even if everybody agree that both kastom and Christianity are good as creations of God. The sole mention to a non Christian people of the book was for the little Baha’i community usually known as man jiu or man Abraham. Some Tannese already discovered Islam in the capital Port-Vila, but on Tanna it was totally absent in the imaginary of local grass-roots. Things radically changed after the 9/11. Beside a frequent appraisal of Ben Laden and what was considered as his legitimate defense of the kastom of the 'man muslam', more islanders turned to Islam. Tanna today has thus become a coveted destination for Muslim missionaries. I will firstly focus in my paper on the main religious, political and economical aspects of that phenomenon, on the way Islam has been largely converted to local cultural realities and adapted to the island political game, while the Muslim community also became one of the wealthiest in the island. This success story will be examined through the explanations given by Tannese Muslim themselves and those given by members of other denominations.