It's enough to have faith in one aspect of God. You have faith in God without form. That is very good. But never get into your head that your faith alone is true and every other is false. Know for certain that God without form is real and that God with form is also real. Then hold fast to whichever faith appeals to you.
"Ramakrishna and His Disciples". Book by Christopher Isherwood, p. 263, 1965.