The earliest Christians met in pprivate houses because they did not have the funds to construct special churches, nor the number to justify them. However, there is evidence of possibly two purpose-built Christian churches from as early as the first century. By the third century, church buildings were becoming quite common.
House fellowship is where Christians worship with fellow-christians in private houses and not in Church buildings.
At the early churches. actually They met in houses to sneek around they also met somewhere else but i dont remember but it wasnt the early churches
Christians can mingle by going to different churches to meet other Christians. Otherwise, there are Christian charities where one could volunteer and where one might meet other Christians.
Thousands of homes have private owners
private single family houses
Houses of Parliament
private single family houses
The Houses of the Oireachtas, which are the Dáil and the Seanad.
In private homes or isolated places.
They don't have to meet in churches - the first Christians met in each others' homes, shared a communal meal, and went to synagogue like the good Jews they were.
When it rained outside, yes.
Dating introduction services are available for Christians who are single to enable them to meet like minded people. Christian Mingle is an online Christian dating service. Alternately dioceses sometimes organised social events or holidays to enable single Christians to meet each other.