Slaughtering some(sheeps, cattles, camels) animals in a certain time(religious holiday) is a worship. Slaughtering an animal in religious holiday is an obligation(order of God) for a sufficient reach Muslim. God does not order to slaughter animal in meaning of sacrifice. Ofcourse performing order of God is worship and give good deeds for a believer. In that manner slaughtering may earn good deeds. And every good deed should be redemption for sins.
Muslims distribute some part meats of slaughtering animal to poor people. That is the mean reason of order of God. Otherwise God do not need anything.
37-Their meat will not reach Allah, nor will their blood, but what reaches Him is piety from you. Thus have We subjected them to you that you may glorify Allah for that [to] which He has guided you; and give good tidings to the doers of good. Al-Hajj(22)