answer needs a little elaboration:
human being who believes in Allah, there are two distinct spheres of
interaction in which relationships come into existence. The first sphere
covers a person's relationship with Allah, while the second one constitutes a
person's relationship with his fellow human beings. Islam and all divinely
revealed religions nothing but guide human intellect in these two spheres. A
person's relationship with Allah manifests itself in worship, which in Islam
has some distinct forms. Similarly, a person's relationship with his brethren
takes the form of social interaction, which again has many areas. Total or
partial negation of any one of these spheres results in an unbalanced life.
Extremism in the first sphere breeds monasticism and ascetism while extremism
in the second one breeds materialism. Islam wants every person to create a
balance in his life by giving each sphere its due. Similarly, it wants a
person to undertake the various prescribed forms of interaction in both the
spheres since each has a definite purpose.
In the first
sphere, Islam has prescribed specific forms of worship of which one form
cannot replace the other, since each has its own purpose and objective. Animal
Sacrifice is one such form of worship. It has an underlying philosophy which
must be well be appreciated in order to do it in letter and spirit. Just as
salāt cannot replace zakāt and vice versa, animal sacrifice also cannot be
replaced by zakāt or charity. What animal sacrifce induces in a person, zakāt
or salāt or hajj do not.
d'etre for animal sacrifice on Eid is to commemorate a great event which
depicts an extraordinary expression of submission to the command of Allah --
the essence of Islam. The Prophet Abraham (sws) while obeying the Almighty set
a platinum example of this submission. When we offer an animal in sacrifice,
we actually symbolize our intention that we are ready to submit ourselves to
Allah in any way that may be required by Him, just as His great Prophet
Abraham (sws) had once done so with spirit and splendour, glory and grandeur.