Again, being an Indonesian citizen does not make you automatically a Muslim.Just because you are a citizen of Indonesia does not mean that you are a muslim.Did he go to a public school in Indonesia? Only citizens of Indonesia can attend public school. Islam is taught in public school in Indonesia as it is an islamic nation. If you are correct and obama went to public school in Indonesia, he was a citizen of Indonesia and a muslim.
Muslim 86.1%, Protestant 5.7%, Roman Catholic 3%, Hindu 1.8%, other or unspecified 3.4% (2000 census)
https://www.cia.gov/library/publications/the-world-factbook/geos/id.html
The PUBLIC schools are religious and under the authority of the Ministry of Religious Affairs.
Education in Indonesia is under the responsibility of the Ministry of Education and Culture (Kementerian Pendidikan dan Kebudayaan or Kemdikbud) and the Ministry of Religious Affairs (Kementerian Agama or Kemenag). In Indonesia, all citizens must undertake nine years of compulsory education, six years at elementary level and three in junior high school. Islamic schools are the responsibility of the Ministry of Religious Affairs.
btw do you have a link for the info on Islamic education in Indonesia that you copied?