With all due respect to BigCountry, this is for school, so I would suggest using facts and logic, rather than religious texts, unless you attend a religious school, where that kind of argument will carry a lot of weight.

Here are a few facts that you might be able to use.

There were approximately 5,000 deer-related vehicle accidents in Fairfax County, Virginia alone in 2004.

Biologists estimate that there are approximately twice as many deer in Virginia now as there were when Jamestown was first settled in 1607 (400 year anniversary!). But the deer’s natural habitat has been greatly reduced, due to human population pressures.

Deer eat lots of farm crops, causing significant economic damage to a struggling sector of the economy.

Humans have essentially wiped out most of the deer’s natural predators. This means that the deer population would explode if humans did not keep their populations in check. If the deer population gets out of control:
1) There will there be more economic damage to the agricultural sector of the economy.
2) There will be more deer-related vehicle accidents, resulting in the loss of not only money spent on car repairs and higher insurance premiums, but also injuries and the loss of human life.
3) In addition to damaging agricultural crops, deer will strip off more and more of the natural vegetation across the land. I can see it in the lack of undergrowth in some areas of the forest where deer populations are high. I believe it was in Austria that the deer population had been getting out of control to the point where the deer were eating back the young tree shoots so that the mature trees were not being replaced. Towns located on the mountainsides depended on thick growths of trees to slow down the avalanches, but the reduced tree populations resulted in entire villages being wiped out by avalanches that would otherwise not have been touched by them.
4) Because of the overgrazing and the stripping of natural habitat, eventually more deer will starve during the winter, a horrible way to die and much worse than a quick arrow or bullet through the heart or lungs.

I hope this helps. Good luck!