Why is the atmosphere essential for life?

If we talk about the outer space, the temperature conditions are highly variable. At those conditions any biotic component or an organism cannot survive. Atmosphere of a planet acts as a barrier against these conditions.

1) It maintains a range of temperature at which organisms can survive.

2) It maintains other factors like steady state of components like water, specific percentage of gases, gravity.

3) Prevents us from the harmful U.V radiations coming from sun.

4) Maintains surface components like soil which are essential for survival.