Posts on Facebook, Twitter, and popular wiki question sites often humorously ponder what exactly an atheist is supposed to do should they find themselves in court preparing to testify. Obviously an atheist cannot swear on the Holy Bible, so what prevents atheists from perjuring without fear of eternal damnation?
Before the question of an atheist lying under whatever oath they may or may not take is addressed, please open your mind to the possibility that just maybe there have been Christians that have lied despite their sworn oath to God on the Bible. Most people, regardless of their religious denomination, engage in “sinful” behaviors because it suits their basic needs at that very moment. But that’s okay. Christians have accepted that they are forever flawed beings that fall short of the glory of God and can easily ask for forgiveness. (Spoiler Alert: Forgiveness is almost always granted by the voices in their heads.)
Having considered that, does it really matter if anyone swears an oath to a deity on a holy book? If lying under that oath will best serve their interests at that moment, they will do so. And in the case of Christianity, there is an easy method of redemption already in place if they should bear false witness. Compare this to the plight of an atheist, who cannot so easily wash their hands of their intentional deceit. An atheist must live with the consequences of their decisions unlike Christians, who can blame their misdeeds on Satan or mumble some conciliatory words with clasped hands to make their problems disappear.
In conclusion, any person, believer or otherwise, will lie under oath if it serves their needs. The key difference is that an atheist will carry the burden of their decision to do so for the rest of their life. The Christian on the other hand can distance themselves from their deplorable act of hypocrisy by calling upon the death of a martyr two millenia ago. How convenient.