It is true that the way to God is only through mind but that does make idol worship redundant.

As you must be aware, God although present everywhere, his divine experience constantly eludes us. The problem lies in the perception of God.
The same universe is perceived as full of excitement and divine bliss by saints.
For us, it is not so. To purify the heart, one must try to look divinity in each and everything around, which is difficult in initial stage. In such cases idol worship is a very useful way of diverting inner mind to God with the help of outer stimulus.

As one attains perfection, he or she extends the habit to living beings and other inanimate matter. For this exercise of heart purification, one is also in need of a person who has acquired divine powers. It because the job of purification of heart is a stupendous task. To think that material soul will do it on its own is like an ant thinking that it can lift the Himalayas.

The point is idol worship is useful although not essential and many have attained perfection this way.