An honest, carefully examined conviction can never be immoral. On the contrary, the scrupulous use of one's reason is a supreme virtue. This is a matter of personal responsibility. Only you, the individual, can decide whether to live your life with meaning and purpose. Pushing the responsibility onto a mysterious god is an escape, not a solution.
Atheism is important because it is reasonable, and reason is of crucial importance in human affairs.
Atheism is an alternative to the morass of irrational, antimind doctrines found in various religions. Because you owe it to yourself to examine the issue of religious belief carefully and to reach the best judgment you can. Never, never doubt the efficacy of your mind. Never allow others, through pressure or intimidation, to cloud your judgment. If you decide that atheism is a reasonable position, then adopt it with pride and dignity.