In 2005, according to figures compiled by the South Korean National Statistical Office, 46.5% of the population were classified as Irreligious, compared to 22.8% Buddhists, 18.3% Protestants, 10.9% Catholics, and 1.7% Other religions.
According to a 2012 Gallup International poll 15% of South Korean people were convinced atheists, up from 11% in its previous survey in 2005. This made South Korea the joint 5th most atheistic country of the 57 countries surveyed in 2012, tied with Germany on 15%, and behind France on 29%, the Czech Republic on 30%, Japan on 31%, and China on 47%. The number of South Koreans describing themselves as religious dropped 6% from 58% to 52% between the 2005 and 2012 surveys, leaving South Korea joint 17th least religious of the 57 countries surveyed in 2012. The complete 2012 figures for South Korea were 52% of people describing themselves as 'a religious person', 31% as 'not a religious person', 15% as 'a convinced atheist', and 2% as 'Don't know/No response'. For comparison, the global average figures for all 57 countries surveyed in 2012, weighted by population, were 59% of people describing themselves as 'a religious person', 23% as 'not a religious person', 13% as 'a convinced atheist', and 5% as 'Don't know/No response'.
Note however that in the afore-mentioned surveys, the figures for 'Not a religious person' (and also the figures for 'convinced atheists', though to a much lesser extent) include significant numbers of people who nevertheless also describe themselves as Christians, Muslims, Buddhists, etc., How this applies to the South Korean religious landscape is uncertain, as the published numbers do not represent numbers for South Korea, but global averages. Among these global average numbers are the following: Buddhists—97% religious person, 2% not a religious person, 0% convinced atheist, and 1% 'Don't know/No response'. Protestant—83% religious person, 14% not a religious person, 1% convinced atheist, and 2% 'Don't know/No response'. Roman Catholic—81% religious person, 16% not a religious person, 1% convinced atheist, and 2% 'Don't know/No response'. 'Nothing' (No religion) -- 3% religious person, 47% not a religious person, 45% convinced atheist, and 6% 'Don't know/No response'. There can be many reasons for what some may see as the apparent self-contradictions in such positions, such as differing understandings of the meanings of words like 'religious' and 'religion', or 'atheist' and 'atheism', a major problem in discussions related to religion.