The church at 252 Park Street was not demolished. It is still standing and it is still a church. It is now a Latino Protestant church, unsure what denomination.
Before it was the funky pre-Christian Polish church, it was the Central Unitarian Church, named after Central Ave. That congregation moved to Forest Ave, Paramus, next to Van Saun Park. It is still called the Central Unitarian Church.
The church at 252 Park Street was abandoned and vacant from around 1980 to around early 1990's, overgrown, roof collapsing, completely deteriorated. Same for the house on the corner of Central Ave. The new congregation bought the site for almost nothing, during the last real estate collapse (early 90's) and renovated both buildings slowly over almost 10 years.
As for the demolition, you may be confusing wrong corner of Park Street. One block up the Gateway School was demolished to build Park Renaissance, 300 Park Street.