Have ye suffered so many things in vain? if it be yet in vain.
Have ye suffered so many things - namely, persecution from Jews and from fellow-countrymen, incited by the Jews: evidences that ye 'began with the Spirit' (1 Thessalonians 2:13-14).
In vain, х eikee (G1500)] - needlessly; since ye might have avoided them by professing Judaism. Or, shall ye, by falling from grace, lose the reward promised for your sufferings, so that they shall be "in vain?" (Galatians 4:11; 1 Corinthians 15:2; 1 Corinthians 15:17-19; 1 Corinthians 15:29-32; 2 Thessalonians 1:5-7; 2 John 1:8.)
Yet - rather, 'if indeed (or at least) it be really х eige (G1489) kai (G2532)] in vain' (Ellicott). Paul mitigates the preceding words. I will not think that ye will make your sufferings in vain, but that ye will return from legalism to grace.