Few would disagree that the life Jesus lived as portrayed in the Bible is a good example to live by. I would go further and argue it is the best example to live by, almost objectively so. To me, the questions often debated on these forums are almost irrelevant. It almost doesn't matter whether or not Jesus existed, or whether or not Jesus was the Son of God and performed miracles. We will likely never be able to know the answers to these questions definitively. If we die and our suspicions are confirmed that there is no God, will we have regretted living a life like Jesus did, leaving the world in a better state than when we entered it? I see no reason why that would be the case.
Too often, when atheists reject the hypocritical religious moral busybodies, the corrupt megachurch pastors fleecing their flocks, the outright crimes committed by some religious people and in the name of their religions, we tend to reject the concept wholesale without retaining what can be good about it. Atheism is just a rejection of belief in a god and therefore does not answer any moral questions; it isn't intended to. That isn't to say that atheists lack morality because that's not true either. But we tend to piece one out based on reason loosely based on the Golden Rule. But is this enough? I don't think so either.
Having a moral code based on reason is a good thing, but without the impetus to actually put it into practice in all situations, then we end up living our lives in cruise control at the whims of our desires. Most of us aren't terrible people. The harm we inflict on most people tends not to be intentional. Yet, we still harm others out of a sense of opportunity, out of a desire for justice or vengeance, or we still harbour hatred for others. By actively making an effort to live more like Jesus did, we might fall short, but the attempt would most certainly make our lives immeasurably better. So I pose the question again: Why shouldn't we atheists follow Jesus?