The original statement is Yeshaya 45:7
יוֹצֵ֥ר אוֹר֙ וּבוֹרֵ֣א חֹ֔שֶׁךְ עֹשֶׂ֥ה שָׁל֖וֹם וּב֣וֹרֵא רָ֑ע
אֲנִ֥י יְהֹוָ֖ה עֹשֶׂ֥ה כָל־אֵֽלֶּה:
Who forms light and creates darkness, Who makes peace and creates
evil; I am the Lord, Who makes all these.
In order to not refer to evil explicitly, the word רָ֑ע is changed to את הכל as is explained Berachos 11b
The literary style of the nevi'im often involves two similar phrases that involve differing connotations and deep meanings. Each part of the phrase actually has a slightly different message to convey.
For example, light and darkness could refer to the different elements of the physical universe showing that Hashem created all of these (apparently) conflicting elements as a unified whole. Shalom (good) and Ra (evil) on the other hand are conflicting elements of the spiritual universe. Even though they appear to be totally, antithetical, Hashem created to possibility of evil in order to have a creation that allows for bechiras chofshis (free will - mankind).
Kara writes that this shows that Hashem created the different humors in order to have the world in balance. When man allows the humors to fall out of balance, we have evil.
Saadia Gaon points out this dualism is expressed by Zoroastrianism in the existence of two feuding supreme deities. Radak also points this out and says that Hashem is telling us that he created all these elements no matter how they appear to be in conflict. Even modern religions give the evil one the free will to rebel against the creator and attempt to tear down good.
Malbim goes into this at length.