‘For this is acceptable, if for conscience toward God a man endures griefs, suffering wrongfully.'
But if a man has to endure griefs and suffer wrongfully because he is being conscientious towards God, then that also is something that is well pleasing (gracious behaviour) to God. It will earn His gracious favour in return.
Here we get the first hint of the possibility of persecution for righteousness' sake, for here the thought is of some who suffer for conscience' sake, and in the next verse it is for ‘doing well'. This might be seen as suggesting persecution because they were Christians and worshipped Christ. Such a situation could easily arise for example, where a Christian was unwilling to honour the gods worshipped by the household, or to engage in the emperor worship which was so popular in the eastern empire. A polytheist would be unable to understand why a Christian could not both worship his own God, and still pay due honour to his master's household gods and the emperor. Most servants who followed other religions would have found no problem with doing both. Such an attitude might well therefore have been seen, at the best as being the result of his being awkward, and at the worst as resulting from his being deliberately blasphemous and rebellious.
‘This is acceptable (seen as gracious)' means basically that the servant is behaving in a way that is well pleasing to God. For such a person to suffer persecution simply because he followed his conscience would indeed be pleasing to God.