Wherein you greatly rejoice, though now for a little while, if need be, you have been put to grief in various trials,
If need be — ει δεον εστι. If it be necessary - if your situation and circumstances be such that you are exposed to trials and persecutions which you cannot avoid, unless God were to work a miracle for your deliverance, which would not be for your ultimate good, as he purposes to turn all your trials and difficulties to your advantage.