The custom of removing shoes is so essential to Japanese life that it is built into the architecture of houses, and many other kinds of buildings.
At the entrance way of an house is the genkan, an area of floorspace on a lower level to the rest of the house. This is considered to be outside, not inside. Hence you enter the genkan with your shoes on then remove them as you enter the house. You are not supposed to touch the genkan floor with your socks or barefeet, you raise your foot onto the hallway one your shoe is off. However, my hosts, the Eliotts break that rule, as their house is attached to the church building and separated only by the genkan. It would be pretty inconvenient to put shoes on and take them off again ever time they needed to go into the church (which is where I sleep).
In a western house you could use a porch as a genkan, however, the Japanese often have western style porches in addition to their genkans, so they do not remove their shoes in their porches if they have them.