It is important to identify the specific idea of god that the individual or group believes in along with associated beliefs and texts. Avoid personal attacks such as doubting the sincerity of faith, intelligence or personal spiritual experiences and concentrate on the validity of what they believe in.
The emotional shortcomings and needs that are fulfilled by the belief such as fear of death and the unknown, knowing that someone is looking out for you and an explanation and order of all things.
Faith: Define faith as a belief based on want without emphasis on facts or evidence and demonstrate it's extreme importance in belief in God. more about FAITH
Feelings and Experiences: People who experience specific feelings they associate with God or other spiritual beings are probably valid in that they did feel something. However people of all faiths and practices feel things and this is evidence more of it being a psychological condition and interpretation rather than an authentic supernatural experience because they all believe in different things.
The spiritual sensations created by prayer, meditation and other phenomena associated with concentration, belief, conditioning and illness.
The problems created by the definition and actions of a specific god.
Problem of Evil
Perfection creating imperfection
Need to create and manipulate
The problems and errors created by the sacred text(s) that describe the god and are ascribed to him.
History of the text: creation of the text, problems with translation, politics, versions, excluded texts and lack of objective recordings of spiritual phenomena.
Historical problems: parts of the text that differ from accepted history.
Scientific problems: parts that contradict scientific findings.
Overlooked passages: parts of the text that are often overlooked because they do not fit present ideas such as slavery, treatment of women, human/ animal sacrifice, punishments, rituals and other rules.
The writers: explain that the writers were simply recording oral traditions or may have had an objective to warp the truth.
"It ain't the parts of the Bible that I can't understand that bother me, it is the parts that I do understand." - Mark Twain
"No man ever believes that the Bible means what it says; he is always convinced that it says what he means." - George Bernard Shaw
Demonstrate the similarities of the ideas of God and associated texts to others that the individual or group rejects.
"I contend that we are both atheists. I just believe in one fewer god than you do. When you understand why you dismiss all the other possible gods, you will understand why I dismiss yours."
-- Stephen Roberts
6. Science/ Education:
Science cannot be used to outright disprove the existence of God but can be used to show that belief in God is not needed to understand the world around us. Science creates a better world for humanity.
Explanations: God has always been used to explain what we do not understand. As science explains more and more of how and why something happens the less there is attributed to God.
Educated people & Belief: Studies show that the more educated an individual, the less likely he is to be deeply religious or to even believe in a god.
"Creationists make it sound like a 'theory' is something you dreamt up after being drunk all night." - Isaac Asamov
"Gods are fragile things; they may be killed by a whiff of science or a dose of common sense."
-- Chapman Cohen
7. Ethics/ Morals:
As much as believers want to argue that ethics are taught by God the truth is that ethics transcend religion and culture except for the rules that specifically serve a religion. They are derived from natural laws that allow for family, community and social interaction.