At risk of bursting any atheistic bubbles, let me express some points gleaned from the Bible.
1) No Christian can accept peoples' claims to be atheists or agnostics. Such claims contradict what the Bible tells us about human nature. Wherever we go, Christians have to assume that there is a divinely implanted awareness of God in every human soul.
2) Christians can take it for granted that basic religious concepts such as God, eternity, holiness, sin and judgment are meaningful to all men and women. To begin our evangelism by trying to get behind this framework (by setting out to prove that God exists) is to walk into a philosophical maze. Christians should not confuse knowledge of God (religion) with knowledge of how we know Him (epistemology). Unfortunately, on here a lot of Christians make that mistake.
3) All Christian witness must start from the assumption that 'the seed of religion' exists in every human heart. All people have a sense of the holy, of the spiritual. Everyone has a feeling of dependence. All have God's law within their hearts. They all know that they are answerable to God. No matter how loudly they protest to the contrary! Christians are not called to instil these instincts into people. Our responsibility is to build on the foundation which God has already laid.
We care about atheists to the extent that we share the good news of Jesus Christ with them, so that they might come to know the love of God. We make no difference between sharing that with atheists as we do with any other group of people.
Behold Your God by Donald Macleod pp 26-27 (Christian Focus 1990)