Question

Why was West Germany accepted into NATO in 1955?

Answer 1

i think to prevent communism from spreading to West Germany

Answer 2

The biggest reason was because if the Soviets were to invade Europe, they would have to come through West Germany. Since the Soviets were putting troops in East Germany, it was easier to re-arm Germany (even though we did keep large numbers of troops there) than have to be responsible for protecting West Germany while they were unarmed. It also made economic sense to let West Germany pay some of the cost for their security. Finally, by 1955 West Germany was "de-nazified".
(I did not write this, but this person tells exactly why West Germany was accepted into NATO in 1955.)

Nurali is right about the reason on why Soviet may wanted to invade West Germany.

Answer 3

The Federal Republic of Germany (West Germany) was founded 23 May 1949 (1 month after the creation of NATO), including the post-WWII United States, British and French occupation zones and didn't become fully sovereign until 5 May 1955.

Furthermore, the admittance of W. Germany to NATO was seen as offensive by the Soviet Union considering their immense losses during WWII, and who saw Germany as a great threat to their security.There was also resistance from other contemporary leading figures such as the first NATO Secretary General Lord Ismay, who declared their objective as to "keep the Russians out, the Americans in, and the Germans down."