Why shouldn't Ukraine be allowed in Nato?

Is Nato afraid of war with Russia? Wouldn't Nato be a major deterrent to Russians having a war? 😳 why is everyone making Ukraine fight alone?.. if a man was beating a lil boy in the park would you hand the boy a bat instead of fighting the man off yourself?? Why is everyone so full of shit? Putin should have been taken down ages ago for all the crimes and murders he committed in his own country against his own people and political rivals long before these wars.