Do not assume a standard city transfer is available or appropriate. The USCCB guidelines encourage contact with the local Christian community, which in Bethlehem is a significant part of the town. Local operators and official travel information need to inform any actual plan.
The Holy Land · YOUR QUESTION, ANSWERED
Can I visit Bethlehem on a day trip from Jerusalem?
No. Bethlehem is a separate destination about 10 km south of Jerusalem in the West Bank (Palestinian Authority Area A), not a neighborhood of Jerusalem. Passage is through an Israeli checkpoint, and Israeli tour buses and many Israeli guides cannot enter, so groups typically change to a Palestinian guide and vehicle for the Church of the Nativity and the Shepherds’ Field. A pilgrimage normally connects the two as a half-day or full-day excursion, but the route must be checked against current conditions.
Related questions, answered
Can pilgrims visit the Church of the Nativity when access restrictions change?
Access to the Church of the Nativity depends on the Israeli checkpoint at the Jerusalem to Bethlehem road being open to foreign passport holders, which it normally is; the U.S. State Department names Checkpoint 300 near Rachel's Tomb as the only permitted route for its own staff. When restrictions tighten, Israeli guides and vehicles cannot enter, so groups change to a Palestinian guide and coach at the checkpoint, and the Franciscan Custody confirms whether the Latin Masses at St. Catherine's and the Grotto are being celebrated. Check travel.state.gov and the operator's local partner within 48 hours of the visit.
Sources & further readingUSCCB: Holy Land pilgrimage guidelinesU.S. Department of State: travel advisories
Official sources cover institutional information. Suggested pacing and itinerary choices are planning guidance. Check current arrangements for your travel dates.