These structures long preceded Christianity, dating back to fertility ceremonies of ancient pagan religions. Pagan priests used an upright stone, pillar, obelisk, or slender tower to represent the male sex organ. Even today, a stylized union of male and female genitals is found in many cultures.
Notice: “As to the lingam…representing the male organ, in some form or other--as upright stone or pillar or obelisk or slender round tower--it occurs all over the, world, notably in Ireland, and forms such a memorial of the adoration paid by early folk to the great emblem and instrument of human fertility, as cannot be mistaken…Above all, no doubt, there were images of the phallus and the vulva, the great symbols of human fertility” (from the website digital.library).
The Encyclopædia Britannica states this of the spire: “[it is] a symbol of the heavenly aspirations of pious medieval men” (1979). The earliest of man’s “heavenly aspirations” is recorded in Genesis 11:4: “And they said, Go to, let us build a city and a tower, whose top may reach unto heaven…” Speaking of the steeples, spires and other forms of idolatrous high places, God expressed to Israel His contempt for such structures in Leviticus 26:30: “And I will destroy your high places, and cut down your images, and cast your carcasses upon the carcasses of your idols, and my soul shall abhor you.”