It is noted by many that they would not be say Catholics had they been born in a Muslim country.
Is their religion an accident of geography, family, culture and history?
If the answer is yes then we cannot say this is true of all religionists. Some do convert. Others only pretend to follow their religion.
The answer is actually yes and no. You will be put into whatever religion your parents can find or have been put into. When you are raised in a religion, nobody asks you if you want to choose another one. You are not asked if you want to stay but suffer pressure to conform and remain a member. In Ireland, it is taken for granted that every Catholic child will accept confirmation into membership of the Church.
It has been noticed that societies that are wealthy and that enjoy the fruits of technological progress have a higher number of atheists than societies that enjoy less of these securities.
It could be that atheists help society progress.
It could be that people who feel comfortable without God soon forget about him and tend to adopt atheism. Perhaps they have more time and the means to ponder the existence of God and they decide the case for God is wanting.
It could be that there is truth in both.
On the downside, societies that have the highest level of luxury and comfort and the highest atheism suffer from a higher suicide rate.
When belief is caused by factors other than evidence or primarily by factors other than evidence then belief is really not belief at all. It is a crutch caused by conditioning. The person whose belief is about what the evidence points to should be more tolerant than the person whose so-called belief is not.
If your belief is caused by evidence you will inevitably have the following attitude towards the person who disagrees with you, "That person is one of the following - ignorant, not intelligent enough, not right in the head, dishonest". As horrible as the attitude is, it is worse coming from a person whose belief is not grounded on evidence to an adequate degree.