"For it was Christian faith that first taught the male warrior a code of courtesy, compassion, and charity, whose first expression was Christian chivalry, whose later expression was the ideal of the Christian gentleman, and whose underlying ideal has been the equality of women and men in baptism, in faith, and in the promises of God. The Christian ideal of equality before God not only did not erase sexual differentiation, but, on the contrary, rested upon that reality as its foundation."This is getting at something which I have been mulling myself for some time: namely, that equality not only doesn't precludes differences, but actually presupposes them.
This is something which we can see logically, as for example in a math (or physics) class. As a simple example, we can consider the force of friction working on an object (say a block) which is sliding down an inclined plane:
The force of friction is in general determined by the coefficient of friction multiplied by the normal force:
(1) Ff = ck FN
On the other hand, the sum of the forces must be equal to zero if the block is sliding down the incline with a constant velocity, as per Newton's First Law:
(2) Fg + Ff + FN = 0
--> (3) Fgx - Ff = 0 and (4) FN - Fgy = 0; NB bolded quantities are vectors, plain type are scalars.
Thus, we can states that the coefficient of friction ck is in this case equal to the ratio of the magnitude of force of the x-component of gravity to the magnitude of the normal force; of in other words that it is equal to the tangent of the angle A subtending the incline and the ground:
(5) ck = Fgx/FN = tan A
But we should not in so stating forget or even imply that there is no difference between a coefficient of friction and the tangent of an angle. Indeed, the equality between the two is actually conditional, in this, conditional on choosing the exact angel at which the block slides down the ramp at constant velocity. It would be an erroneous statement to identify the coefficient of friction with the tangent of any arbitrary angle, or even with any angle A subtending an inclined plane.
For that matter, it would be an error to identify friction as "the force which is equal to the opposite of the x-component of gravity"-- a restatement of equation (3). There can, after all, exist a nonzero force of friction on a surface which is not inclined, though in this case the x-component of gravity is typically zero. For that matter, there could be some force of friction, and indeed a significant force of friction, in a region in which there is little (virtually none) gravity. Yet, this is an assertion which follows in this case from the premise that equality is the same thing as identity or interchangeability.