George Carlin says that "Atheism is a non-prophet organization".

In death, everyone should have their wishes and beliefs respected, even if you don’t have a religion. While the families of some atheists perform secular ceremonies for their loved ones, many are uncomfortable organizing such an event, and are unsure of how to proceed. So these families turn to religious leaders, such as pastors, to organize one and request the ceremony remain non-religious. According to some accounts, leaders of faith will insert their own religious beliefs and ceremonies, some even go as far as saying the deceased will burn in hell for not accepting their religion. This kind of force-fed-faith is not enjoyable for anyone attending, and is not giving the deceased the respect they deserve. So when looking for secular ceremonies, try to find alternatives to religious leaders to avoid this, or run one yourself and make the ceremony whatever the deceased would have wanted.

Read more:

Athiest Ceremonies | Think Atheist

An Atheist Funeral | A Song of Ice and Fire