Sefer Siach Zekeinim (Chelek 2, page 186) relates that one Pesach, when Rav Yissochor Dov of Belz zy’a reached ‘Shfoch Chomascha’ he sent one of the children to open the door for Eliyahu Hanavi. When the child returned, the Rebbe asked, ‘Did you see Eliyahu?’
The child answered, ‘No.’
The Rebbe’s grandson, Rav Yochanon Twersky zt’l then asked, ‘Is it really true that one can see Eliyahu Hanavi?’
The Rebbe answered, ‘Yes. He can be seen. But someone who believes without seeing is a lot loftier than one you sees.’
He quoted the pasuk (Shemos 14:31) that says: ‘And Yisroel saw…and they believed’, and said that even though they saw the miracles with their eyes, and they did not need to have emunah, they still had blind emunah in Hashem.
This idea also explains the pasuk (Bereishis 15:6) that says about Avrohom Avinu: ‘And he believed in Hashem and it was considered for him as an act of tzedakah.’ This can be understood to mean that Hashem lifted Avrohom up to the Heavens, and he saw everything, but he still had simple emunah in Hashem, and this was considered an act of righteousness.