Maggie's Farm

The architectural origin of the steeple lies in the belltower, and the origin of the belltower in the watchtower.

Medieval watchtowers, like this one in Umbria,

 and this one in San Gimignano, the town of towers,

used bells, guns, and fire to signal each other in time of trouble. Church belltowers, at first identical to watchtowers, were often separate from church buildings through the early renaissance. You had to place those bells up high to send out the sound. Here's a famous one, which is the belltower of Pisa's Duomo (c. 1100):

In time, the belltowers were integrated into the architecture of church and cathedral buildings. Without clocks and watches, you couldn't be called to church or prayer - nor would you know what time it was (except for sundials) without the bells sounding across the villages and fields. And they were a regular reminder of Christ's presence during the day. (But how did the bell-ringers know the time? That's another subject.)

Canterbury Cathedral (c. 1300) has the Gothic integration of tower. It took 63 men to ring its heavy bells; six men alone to ring the heaviest:

More modest English parish churches had bell towers on the roof (Holy Cross, Greenford Magna, Middlesex - much of the building c. 1500):

Puritan (Congregationalist) Meeting Houses in the US typically had no steeples, as part of their purifying their congregations from papistry, vanity, and other fanciness (no bells, no stained windows, no singing, 6-hour sermons, etc). They didn't even want to call them "churches, " and you went to "meeting", not to church, where the God of Grace played second fiddle to the God of Truth. This is the Rocky Hill Meeting House (c. 1785) in Amesbury, MA:

By the early 1800s, steeple bell towers came back into acceptance in the US, along with singing. I can imagine the debates between the stodgy old-timers and the young folks in their Building Committees. Many old New England churches are meeting houses with steeples (and pillared porticos too) added generations later, leading to steeple engineering problems in later years. Here's an example of an added steeple in Alford, MA (c. 1740):

Belfries, containing the bells and their mechanisms (and bats), usually have/had louvers to direct the sound up and away from the church itself. Oftentimes a steeple - the tower which supports the belfry, is roofed by an elegant spire, leading to the stereotypical appearance of the 19th Century New England Congregational church - which has since been copied by all sorts of denominations including Catholics - seemingly unaware of the Puritan, anti-Anglican, anti-hierarchical, and anti-Papist theological origin of the architecture:

We always need to be reminded that a "church" is not a building - it's a congregation of people who seek God through Christ ("whenever two or three of you are gathered together"). The building doesn't really matter, but having a special place never hurts. I think the spires are optional. 

Here's a nice piece on church bells.

YouTube of Dylan doing All Along the Watchtower here. (with JJ Jackson, Winston Watson, and Bucky Baxter)