First, Visiting a temple is quite different from visiting any other place. The temple is the best place we visit. That is the place from which we are to gain something invaluable. During our practical life when we go to a minister, we change our mental level and our attitude. Whatever dust has gathered on our shoes, socks or feet are removed by us by striking our feet on the floor outside his chamber or residence. There is a hygienic reason behind this. Cleanliness is as essential as preserving sanctity.

Shoes move on various surfaces both dirty and clean A person may be sitting near a dirty pool and flies may be repeatedly resting on his body. Another clean person occupying a decent seat may be talking to someone. Our attitude to both of them may be quite different because one is dirty while the other is clean. This cleanliness is of prime necessity to preserve the sanctity of the temple, which is the holy home of God.

Moreover when we go to a temple or approach the holy thron ...more

Same reason when we enter our home .............. in home , it is for keeping the environment clean ...in temple for cleaning our mind and soul

To show respect for the deity

To keep the place clean and as a respect to temples diety

As a mark of respect and then hygiene

Temples are sacred places and we should enter into a temple clean... shoes carry dirt and germs because we walk wearing them on the roads and toilets... so we are suppose to leave our shoes or any foot wear and wash our feet before entering into a temple... also they are made of leather, animal skin which are considered as non sacred things according to Hinduism....
in the same way we treat our house as a temple because it protect us from rain, sun, cold, thieves etc.... so we are not allowed to walk into our house with foot wear.... :)