You have to think and see the truth for yourself.
Avoid a long and difficult examination of which competing religious and spiritual claims are right and depend on this book as your reason understands it. Take for example, the controversy between Mormons and Christians. Each side has an answer for the other so it is hard work to sort out who is twisting logic and taking forbidden shortcuts in it. If you base your world-view on people's testimony you will never be satisfied and fully sane because disagreement and confusion abound. You need to be healthily sceptical.
So how are we to know which of the many philosophies or religions of the world is right? By the unique simplicity and commonsense of the teaching and it must be something that is easily proven to be true for we cannot refute every error people make and so we focus on the basics. Only Humanism is able to live up to this standard.
All our simplicity protects people from being misled and manipulated for it leaves little room for error and saves them from the clutches of those who twist the truth to give them convincing evidences for this and for that that are full of flaws and clever deceptions. The Humanist just needs to remember and understand the basics of the book and that is all.
Atheism is the truth.
Even if there were no proof in our favour it would be clear that it is safest to follow our philosophy and so we should. If God is good he will understand and reward our sincere efforts. Fire can burn you even if you sincerely believe it will not. This does not prove that God will condemn you for meaning well for he is not letting you be burned for meaning well but because he will not change reality all the time to suit your beliefs for that would be chaotic.
Religion is men telling me how to live and influencing me in the name of God. Nobody wants God unless they find him attractive which means they are only after their own gratification so their feelings are the real God for they are the real goal. Therefore to serve God is really to serve the men who make the rules in his name. Do not be manipulated but be free of religion.
I must promote secularism (separation of religion and state) because it looks at problems and their solutions only on the human level. I must resolve to correct anyone who opposes secularism. If we start bringing in gods and magic into our politics we will end up getting nowhere for no two people can agree on what their deities want us to do so it is simpler to keep the state secular. It’s hard enough to decide and do the right thing when you take one world into account without involving God’s world as well. There is no other way. It is not enough to stop the Church meddling in the affairs of the state – the Church will still be able to manipulate the state if it has an undue influence on the people. The taxpayer should not have to pay the state and the Church to let the Church spread its propaganda in the schools to the vulnerable and easily conditioned. It is important to get people to look with clarity at all issues from as many angles as possible so the secular voice must be raised caringly but loudly and firmly.