If you mean there is no if/then keywords in the language then yes, PROLOG is one. But if you mean there is no branching, no comparison (conditional branching)

If you mean there is no if/then keywords in the language then yes, PROLOG is one. But if you mean there is no branching, no comparison (conditional branching) then NO. Even the most basic Turing machine has to decide, and to be able to decide you have to compare and do a form of branching (halt,left or right). Therefore, all “proper” programming languages must have conditional branching.