N.J. Const. art. VIII, § 1, ¶ 2

Exemption from taxation may be granted only by general laws. Until otherwise provided by law all exemptions from taxation validly granted and now in existence shall be continued. Exemptions from taxation may be altered or repealed, except those exempting real and personal property used exclusively for religious, educational, charitable or cemetery purposes, as defined by law, and owned by any corporation or association organized and conducted exclusively for one or more of such purposes and not operating for profit.