If you're referring to *Christian* faiths that use the term, there isn't an official abbreviation for the reason that "Elder" *is not used as a personal title*.

Some Christian denominations use the term "elder" because the biblical records of first-century congregations say that "older men" took the lead and did not accept "honorific titles". So whereas some denominations do say, for example, "the Reverend Smith" or "Father Jones", elders are not normally addressed using the title. They may be known as "an elder" in their faith, but in secular life use titles like "Mr".

Also worth noting is that countries which recognise titles like "reverend" do so only if the person is ordained as a minister of a recognised religion, but Christian elders are not *ordained* as such. "Elder" is *relative* term - that is, it recognises *experience*. Some such faiths consider *all* of their members to be ordained ministers, and elders are just appointed for their experience.

I quickly researched the use of the term in the Church of Latter-Day Saints (Mormons), as I have seen their missionaries wearing name-badges that say "Elder Jones" on them. According to the Wikipedia entry on the church "The title "Elder" is not normally used as a personal title (e.g., Elder Evans, Elder Johnson), *except by the LDS Church's general authorities, area seventies, and full-time male missionaries*." So apparently their use of "elder" as a title is for internal use only and they do not use the term in secular life.