How painful it was to the apostle that those who once loved him so deeply had become suspicious and even hostile towards him, because of the poisonous words of the Judaizers which they had allowed to enter their hearts! They should have been prepared for such an attack on their faith, and they ought to have been able to withstand it, for they possessed all necessary armour to defend them. Their failure to do so was entirely their fault, but it caused Paul much sorrow.