Is CBP required to provide reasonable accommodation for religious beliefs or practices?

Yes. It is a violation of Title VII of the Civil Rights Act of 1964 to fail to provide a reasonable accommodation for the religious beliefs and/or practices of employees and applicants for employment unless providing a reasonable accommodation would result in undue hardship to CBP. Undue hardship means more than de minimis cost or burden on the operation of CBP. Note that this is a lower standard to meet than undue hardship under the Rehabilitation Act, which is defined in that statute as "significant difficulty or expense."