For the possible relationship of the movements of Timothy and Silas in Acts and in Paul’s writings (1 Thessalonians 2.17–3.5), see various commentaries. It must be remembered that both Luke and Paul have included in their records only what was of concern and importance to them; neither has tried to give an exhaustive account of all that took place. This is the last time that Silas is mentioned in Acts. The introductory clause when Silas and Timothy arrived from Macedonia is a very important transitional device, since it marks the time when Paul gave up working with Aquila and Priscilla and devoted himself full time to preaching the message.
Gave his whole time to translates a verb which literally means “to hold together” (see 7.57; 28.8); here it is used in the sense of “give (one’s) whole time to” or “to be completely occupied with.” Gave his whole time to may also be rendered as “did nothing else but” or “worked only at.”
In a number of languages one cannot speak of preaching the message. There must be some kind of goal or content of the message—for example, “the message about Jesus.”
In this context the verb testifying may be equivalent to “showing clearly” or “explaining carefully.”
When in Greek two nouns occur together as subject and as predicate complement, it is normal for the subject to occur with the article and for the predicate to be without the article. Therefore, Jesus is the Messiah may be translated as “the Messiah is Jesus,” since the definite article appears with Messiah. As some commentators have suggested, the Christian missionaries had to begin their preaching in the Jewish synagogues with the known, the Messiah, and go from there to the unknown, Jesus, which would account for this construction in Greek. As in so many languages, the subject expression normally marks given information, while the predicate identifies new information. It is on this basis that one may argue that this final clause may be rendered as “the Messiah, whom they know about, was indeed Jesus,” since Jesus would have been the unknown element as far as Paul’s hearers were concerned. However, this type of order would seem quite strange to the average reader of the New Testament who would be much more familiar with the person of Jesus than he would with the designation of Jesus as the Messiah. Therefore, to the reader, it is the Messiahship of Jesus which is presumably the new information, while Jesus, as a historical person, is well accepted as given information. It is for this reason that so many translations (for example, Phillips, Luther, La Sainte Bible: Nouvelle version Segond révisée, An American Translation*, Zürcher Bibel), employ the arrangement “Jesus was the Messiah.” Others retain the Greek structure “the Messiah is Jesus” (Revised Standard Version, New English Bible, Moffatt).
Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on The Acts of the Apostles. (UBS Handbook Series). New York: UBS, 1972. For this and other handbooks for translators see here .