Each person has their own subjective world and a knowledge and belief of the objective reality. There are well-known and straightforward criteria for determining whether a thing belongs to the objective reality or not. The same cannot be said for the subjective world which, by its very definition, is exclusive to each person. Some components of our subjective world, such as "the sensation of seeing red", are elemental in that they represent basic things. These elements are obligatory and imposed upon our subjective world. However, other components of the subjective world, such as a mental model of a God, are inessential.
The range of the inessential components is vast. One type of optional component is a belief in something that, by its definition, is elusive. An example of this type is a belief in the invisible good tree stump in the middle of the lounge room. The good tree stump cannot be seen or felt, and you can walk right through it. But it radiates feelings of goodness to a person whenever the person thinks about it in a positive way. However, the feelings of goodness don't occur if the person questions the existence of the tree stump or doesn't believe the feelings of goodness will occur. The good tree stump is purported to be an element of the objective reality and, indeed, it resides in the lounge room which is in the objective reality. But it is entirely fictional. One can invent such elusive components of the subjective world at will. Surely there is little merit in taking any of them seriously. Religious belief appears to be mainly of the elusive type. An example is that if you don't believe in God then God will not help you. However if you do believe in God you are not guaranteed that your prayers will be answered. One could invent elusive optional subjective components like this at will.
People have adopted many different religions in recorded history. Each religion contradicts another at least in parts. A person's choice of which religion to adopt is overwhelmingly made on the person's inherited culture and general upbringing; this is the "random accident of birth". In this sense a person's choice of religion is random. The same person could equally have adopted one of many mutually contradictory religions had the circumstances of the person's childhood been different. For example, an accident of mistaken identity in the maternity ward at the time the person was born could have resulted in the person being brought up by a family whose religion contradicts the religion of the person's natural family. To stress this point further, the person could be a monotheist or a polytheist depending on such random accidents.
This situation stems from the intrinsically subjective nature of religious belief. It also highlight the shortcomings of its subjective nature, in that it implies that one person can believe any number of religious beliefs, regardless of how contradictory they might be.
Finally, we can look at this from another perspective, from the abandonment as opposed to the adoption of religions. The adoption of one randomly chosen religion implies the abandonment of all others.
Atheists, rather than adopt one randomly chosen religion and abandon all others, instead abandon religions all together.