The phrase "a decisive point in" is correct and usable in written English.
It can be used to indicate a critical moment or location in a discussion, argument, or event that significantly influences the outcome.
Example: "The negotiations reached a decisive point in the discussions, determining the future of the agreement."
Alternatives: "a turning point in" or "a critical juncture in".
"We are at a decisive point in time," he said.
Labour's swift suspension of Ken Livingstone following his inflammatory remarks about Hitler and Zionism may herald a decisive point in the escalating furore over antisemitism.
The official history points to the Montreal Olympics in 1976 as a decisive point in the history of the national anthem.
A circular or "ring" narrative is one in which events come to a decisive point in the middle and then lead back, in parallel fashion, to the point of entry: ABCBA.
"Little is known and even less has been written about this period in Van Gogh's life, but it was a decisive point in his career," said Marie Noble, deputy director of Mons 2015.
Kathleen Gerson, a professor of sociology at New York University whose studies on reshaping family and work were cited by her Norwegian colleague, Ms. Teigen, noted that women's efforts to play an equal part at work and home are at a decisive point in a fast-shifting 21st century "where the new normal is going to be a life that cannot be planned too far in advance".
The brothers, silver medallists at the 2010 world championships, were level at 2-2 in the final six-throw end, but will have to settle for a bronze at best after Eilseu Dos Santos and Jose Pinto Dirceu grabbed a decisive point late on in their BC4 pairs clash.
23 boys aged 16-21 have gathered to learn more about the technical aspects of filmmaking and to share their own stories, personal accounts of young people at a very decisive point in their lives.
If anything, Serena seemed more upset than Venus by the umpiring mistake that gave Karolina Sprem an additional and possibly decisive point in the second-set tiebreak against her sister.
The Promise provides a fly-on-the-wall look at the creative process of a possessed, controlling, almost excessively talented artist at the most decisive point in his career.
It was the decisive point in the Confederate loss at Gettysburg and Lee ordered a retreat back to Virginia the following day.
