The Doctor: When Indifference Becomes Essential

[T]he liberty that the Apostle allows with regard to things that are indifferent ceases the moment they are regarded as essential.  … We read in Acts 16 that Paul agreed to have Timothy circumcised.  but we find in Galatians 2 that Paul refused to have Titus circumcised.  Was he being inconsistent?  Not at all!  Paul had Timothy circumcised in order not to cause offence – the same principle that we have in this chapter.  But he refused to circumcise Titus when he met the Judaizers, because they said that circumcision was essential.  – D. Martyn Lloyd-Jones, Romans Vol. 14, p. 200