Before Adam was created Allah knew man was weak, and the Often-Forgiving is willing to pardon all our shortcomings even if they are as tall as mountains, except for one deed: the injustice of shirk (associating partners with Allah).
To believe in Allah as your Lord is not sufficient if you pray to someone else
Rationalizing shrik as a means of get closer to Allah is still shrik
There is no difference between one who worships stones, pious people, sun and moon, angels, etc. They are in the same boat of shirk
At times of distress, a sincere call for help is only made to Allah (Tawheed)