Why do people sacrifice lambs?

Answer 1

To my knowledge, no Christians sacrifice animals of any kind any longer, since the crusifiction of Christ. Jesus was the final sacrifice. God told us that there are no longer any need for sacrificing animals. Jesus was God's sacrifice that will never need repeating.

Answer 2

Jewish answer: One of the topics in the Torah (Leviticus ch.1-8) is that of sacrifices. Since the Holy Temple doesn't exist today, we don't now offer sacrifices. In earlier times, sacrifices were one of the ways of serving God; a type of manifest prayer. They consisted of bullocks, goats, sheep, rams, turtle-doves, or fine flour, accompanied by an offering of oil and of wine (see Numbers ch.15).Some offerings were obligatory and some were voluntary; some were for the individual and some were for the public. There was one set of offerings which was intended to provide merit for the non-Jewish nations as well.

Some of the ideas included in the sacrifices are:

gratitude (the Shelamim-offering, Leviticus ch.3),

dedication to God (the Olah-offering, Leviticus ch.1),

celebration (the Hagigah-offering during Festivals),

atonement (the sin-offerings, Leviticus ch.4-5),

and public worship (the offerings in Numbers ch.28-29).
Our traditions teach that as long as the sacrifices were offered in the Temple, the world was blessed (Talmud, Ketubot 10b) and atoned for (Sukkah 55b).

Note:
Some people have a misconception that the Prophets were not in favor of sacrifices. This is a mistake. The same Prophet Samuel who said that obedience is more important than offerings (1 Samuel ch.15), himself offered up sacrifices to God (1 Samuel ch.13).
What the Prophets meant was that repentance and obedience to God are essential; they should accompany the sacrifices and cannot be replaced by the sacrifices (or anything else). All of the offerings are intended to be part of a process of drawing near to God. This ideal of offerings together with repentance is explained in the Talmud as well (Berakhot 23a). The Talmud adds that, similar to the offerings, Torah-study also needs to be accompanied by repentance (Berakhot 17a).

Another misconception is that Judaism changed after the Temple's destruction, and "turned from a sacrifice-centered religion" to one of prayer. This too is a mistake. Jews always worshiped in synagogues, even when the Holy Temple stood. Within the Temple premises itself, there were several synagogues. During the Second Temple era, ancient Greek authors attest to the large synagogues that stood in all the countries where Jews lived. The Dioploston in Alexandria, for example, was famous for its size (Talmud, Tosefta Sukkah 4:6). In First Temple times also, synagogues served the same function that they do today (Talmud, Megillah 26b and Berakhot 31a).

See also:

Why was the Temple destroyed?

How has Judaism changed?

Answer 3

Lambs have not been sacrificed in the Jewish religion for the past 1,939 years.

Answer 4

The Bible (mostly in Leviticus) requires a wide variety of sacrifices. No explanation is offered as to why these specific animals were required, but all of them were animals that were grown commercially by farmers in the region. Among the animal sacrifices, bulls, sheep, goats and pigeons are the most prominent, along with meal offerings. Bulls, sheep and goats are explicitly required in various official offerings on behalf of the community. In several cases where individuals are required to bring animals for sacrifice, they are told to bring a sheep, but if they can't afford a sheep, bring a dove (pigeon) an if they can't afford that, bring a meal offering. Christians focus on the Passover lamb, which is indeed required to be a lamb. Why? Well, one obvious guess is that spring is lambing season, so lambs were widely available at that time of year.