Okada is the adoptive daughter (some sources say daughter-in-law; both may be true) of Okama Kotama. Her adoptive father left a Shinto-based religion called Sekai Kyusei Kyo and founded a sect called Sekai Mahikari Bunmei Kyodan in 1959.
After he died in 1974 there was an internal struggle for the leadership of the new religion which she lost to Sekiguchi Sakae. As a result, Okada Keishu founded Sukyo Mahikari in 1978, which is closely related to Sekai Mahikari Bunmei Kyodan in beliefs, but which teaches that she is God's representative on earth.
The religion's official history states that it was the father himself who founded Sukyo Mahikari, but this is not followed by academic students of new Japanese religious movements.
Okada herself adopted a son, Okada Koya, whom she appointed as her representative in 2002, apparently in preparation for her retirement, although continuing to prepare reitual objects for ceremonial use.