Why does it say "Elokei Avraham [Yitzchak v'Yisrael]"?
Malbim: From then, Hashem began to dwell amidst Yisrael.
What will become known today?
Malbim: (a) You are Elokei Yisrael - You oversee them and dwell amidst them [even] in their Tum'ah. (b) I am Your servant. (c) I offered on a Bamah according to Your word.
Why is it important that they know that I am Your servant?
Rashi (37): When You will send me to inform them [that Mashi'ach is coming], they will believe me.
Why did he say "uvi'Dvarcha Asisi"?
Rashi, from Yerushalmi Ta'anis 2:8: I offered on a Bamah when Bamos were forbidden [based on Your command].
Radak: If You answer me with fire from Shamayim, they will know that everything I do is according to Your word. People should not say that the miracles were via witchcraft.