| | Shelter Island Heights, NY | Rockville Centre, NY | United States |
| Percent Religious | 72.6% | 67.7% | 49.4% |
| Baptist | 0.4% | 0.9% | 8.2% |
| Episcopalian | 0.8% | 0.9% | 0.6% |
| Catholic | 60.0% | 52.2% | 19.7% |
| Church of Jesus Christ | 0.2% | 0.2% | 2.1% |
| Lutheran | 2.2% | 1.5% | 2.4% |
| Pentecostal | 0.8% | 0.7% | 1.9% |
| Methodist | 1.7% | 1.2% | 4.0% |
| Presbyterian | 1.0% | 0.7% | 1.7% |
| Other Christian | 2.2% | 1.9% | 6.7% |
| Judaism | 1.4% | 6.0% | 0.7% |
| Eastern | 0.4% | 0.2% | 0.5% |
| Islam | 1.3% | 1.2% | 0.9% |