Explain please?
It's very simple, Vlad - where people have preferences or interests they regard as important to them then whatever these things involve can be dominant factors in their thinking and their lifestyle, so that they live their lives 'according to' what is entailed by these.
For example, back in the day I worked with a chap who freely admitted that the demands of work and family were mere interruptions to his major preoccupation: which in his case was to think about golf, talk about golf, watch other people play golf and of course play golf himself. He also routinely kitted himself out in the silly clothes favoured by golfers when playing, but not otherwise, and constantly held a squeezy spring-like device in his hand 'to improve his grip' (but sadly not of reality, outwith golf-matters).
When it comes to religion undoubtedly there are some who enjoy the ritual and associated activities that can be part of organised religion and, of course, there may be those whose religious convictions are more personal and may not involve much in the way of lifestyle activity. I'd say atheism is probably more like the latter: plenty of thinking perhaps but no real activity since there is nothing to 'do' in respect of atheism whereas there can be in respect of theism (or golf).
Put very simply - religion
can be similar to a hobby in terms of 'doing stuff' in respect of it, so that it may have lifestyle aspects in ways not dissimilar to football enthusiasts who have season tickets and who never miss a game, whereas atheism (as far as I can see) involves no actions or activities at all.