Combating Anti-Semitism Act of 2017 This bill amends the federal criminal code to modify prohibitions with respect to intentionally defacing, damaging, or destroying religious real property. Specifically, the bill broadens the scope of prohibited conduct to also criminalize threats to deface, damage, or destroy religious real property. Additionally, it establishes a criminal penalty—a fine, a prison term of up to five years, or both—for a violation that results in damage or destruction to religious property. Finally, the bill broadens the definition of "religious real property" to include real property owned or leased by a nonprofit, religiously affiliated organization.