Our assumption is that one has accepted that God is, and that He is good. The scenario we are addressing is when a difficult situation has occurred, one may find him/herself challenged:
"I am trying to know that God is good." Stop right there. You are wasting your time, for you are being played by that old serpent the devil. If you were to rewind and play the scenario at a slower speed, you would find that you know what you know, but then the adversary steps in and interjects, as your own thinking, "I am trying to know it," and thereby neutralizes your best effort! If you are trying to know it, you most certainly are not knowing it at all!
Definition: to know - to be aware of the truth or factuality of: be convinced or certain of. (Merriam-Webster online)
Trying to know does not count for anything in the warfare of the flesh and the spirit.
The solution to this invasive "trying" thing is first to notice it, and then kick it the hell out!! God is Mind. God is my mind. God is the only pure mind. God is good, and there is no mind to contradict Him, no mind to doubt the absolute truth. The spirit with which you do this is chronicled in the Bible: "The Word of God is quick and powerful and sharper than any two-edged sword." and Science and Health: "Truth drives error out of all selfhood." and "Truth decapitates error."