Air carrier Captain reported encountering severe turbulence during approach which resulted in a loss of control. The Captain executed the appropriate escape maneuver and diverted to a suitable alternate.

Narrative

The FO (First Officer) was PF initially on the flight. The winds in ZZZ were switching from NW to SE rapidly and increasing in velocity. I asked the FO if he was comfortable flying the approach and he stated he wanted to attempt it; the FO has prior 737 experience at his previous carrier. During the descent briefing; I briefed that if the situation deteriorated to a point I felt it was safer I take over I would verbalize this and it was not a reflection of the FO's performance on his OE (Operating Evaluation). The FO understood and continued to fly the approach. After cleared for the RNP (Required Navigation Performance). [Runway] XXL into ZZZ the aircraft encountered strong moderate turbulence. We had a rapid loss of airspeed along with a rapid pitch up in attitude. I felt it was appropriate at this point to intervene given this was an initial OE flight. I verbalized I was taking control of the aircraft and the FO used proper automation management in the transfer of controls. I advanced the thrust levers to arrest the decaying airspeed. At full thrust the airspeed was still rolling back and approaching the min maneuver tape. I then disconnected the AP (Autopilot) and reduced the pitch to gain back the lost airspeed; our altitude was in no danger of being below the min segment altitude for the approach. I used the recovery technique to stop the airspeed loss and trade altitude loss for speed. The aircraft then rolled right and left 30-40 degrees and shook violently. I had Brief moments of no control of the aircraft. I told the FO we were abandoning the approach; ask ATC for a higher altitude and a vector to the North West; we are diverting to ZZZ1. The FO relayed the request to ATC and reported the severe turbulence. We began a turn to the NW and series of step climbs eventually reaching 13;000ft. After a confirmation with Dispatch over ACARS that ZZZ1 was preferred over ZZZ2 we received a new clearance to ZZZ1 for Weather diversion. During our climb out the aircraft hit pockets of strong turbulence with brief moments of no control and recovery techniques used to arrest fast decaying airspeed and uncommanded rolls due to the turbulence. Flaps were retracted on speed and we did not exceed and flap limit speeds; no passengers or crew were injured. While we experienced a few rapid airspeed losses right to the min maneuver tape; No stall warning indications were encountered. Flight was diverted to ZZZ1 for an uneventful landing. ELB (Electronic Log Book) was made for the severe turbulence encounter with altitude; configuration and airspeed parameters requested by Maintenance Control relayed. No aircraft damage was found