Justine looks rather a girls name (but you are writing "his"). Justin (?)
Anyway, since 1905 is over 100 years ago, civil records may be available on microfilm. Contact a nearby center of the church of Jesus Christ of Latter Day Saints. You may have to browse through several years of civil records (births, mariages, deaths) of Namur (luckily there exist indexes of each year) but very likely you will find them.