| | Rancho Santa Margarita, CA | Cupertino, CA | United States |
| Percent Religious | 46.5% | 44.6% | 49.4% |
| Baptist | 2.7% | 1.2% | 8.2% |
| Episcopalian | 0.4% | 0.5% | 0.6% |
| Catholic | 27.3% | 26.2% | 19.7% |
| Church of Jesus Christ | 2.3% | 1.4% | 2.1% |
| Lutheran | 1.3% | 0.6% | 2.4% |
| Pentecostal | 1.7% | 1.2% | 1.9% |
| Methodist | 0.9% | 1.1% | 4.0% |
| Presbyterian | 1.4% | 0.8% | 1.7% |
| Other Christian | 6.0% | 5.9% | 6.7% |
| Judaism | 0.5% | 0.7% | 0.7% |
| Eastern | 1.1% | 3.8% | 0.5% |
| Islam | 0.8% | 1.1% | 0.9% |