The actual pasuk from sefer Shoftim is worded differently than it is quoted here. The actual pasuk reads as follows:
“And HaShem turned to him and He said, ‘Go with this strength and you shall save [the People of] Israel from the palm of Midian. Behold I have sent you.” (Shoftim: 6; 14)
The defense that Gidon presented to the angel, which led to him being blessed with the strength to save the People of Israel, is stated in the previous pasuk, as follows:
“And Gidon said to him, I beseech you my master, if HaShem is with us, [then] why has all of this occurred to us, and where are all of His wonders, of which our fathers related to us, saying, ‘Did HaShem not bring us up from Egypt, and now HaShem has deserted us and has given us into the palm of Midian?” (Shoftim: 6; 13)
 This teaching is found in Sefer Chareidim, in chapter 66, sif 38, in the new printing.