The sense of belonging is increased when the members of the group have matching items with each other.
The sense of belonging is increased by having similar items with other group members.
"所属意識" = "a sense of belonging"
"共通持っているもの" = "matching items/similar items"
"団体の人" = "members of the group/group members"
"高まる"="increase"
色々な言い方があると思いすが、以下の文章で一番簡単に説明できます。
ご参考ください。
ロシア連邦 
