Keep in mind that these are generic and simplified…
Christianity: Believe in God by faith
Atheism: Believe there is no God by faith
Christianity: Have been raised to believe in God
Atheism: Have been raised to believe in atheism and Darwinism (see Natural Born Atheist)
Christianity: Contradict “every effect has a cause” and therefore are wrong about the existence of God (In all actuality “every effect has a cause” is fallacious, the correct principle is “everything that begins to exist has a cause”—see On the Flying Spaghetti Monster, the Invisible Pink Unicorns, et al.)
Atheism: Contradict “every effect has a cause” and therefore are wrong about the existence of the universe
Christianity: Hold to an inspired text (the Bible)
Atheism: Hold to many non-inspired texts (textbooks, atheistic philosophy, newspapers, and their own thoughts)
Christianity: Believe in absolutes
Atheism: Believe in absolute relativism (see Relativism is a Faith Based Belief Which is Paradoxically Both Relativistic and Absolutist)
Christianity: Think that there is only one way to salvation (see Exclusivism, Part II: Is There Only One Way of Salvation?)
Atheism: Have no such concept but are largely “works based” (in order to make themselves feel good)
Christianity: Believe that they are right and all other religious have some correct concepts of God as well (see Exclusivism, Part I: Is Only One Worldview True?)
Atheism: Believe that they are right and everyone else is wrong
Christianity: Have a concept of what happens after death (resurrection)
Atheism: Have a concept of what happens after death (annihilation)
Christianity: Believe in an ultimate reality (God)
Atheism: Believe in an ultimate reality (themselves)
Christianity: Hold a faith based belief in intelligent, purposeful, creation
Atheism: Hold a faith based belief in random, undirected, spontaneous origin of life
Christianity: Believe in the God of the gaps
Atheism: Believe in the time, or chance, or materialism of the gaps (see The Gap Filler)
Christianity: Believe that all things can ultimately be explained by the existence of God
Atheism: Believe that all things can ultimately be explained by absolute materialism