Maybe the hostilityof the Jews was about to seal their fate--which was justice from God--but the believers had to continue to endure it until the "Day of the Lord" gave them relief (see 2 Thes. 1 on this point). If we saw Paul as a nurturing mother and tutoring father in chapter two, here we see him flooded with heart-tormenting concern. Would those hostilities take these babes away from their faith? Would they bail on Jesus rather than wait for Him?
Sending Timothy to inquire into their condition left Paul alone in discouraging circumstances. The answer from Timothy gave him the relief he craved. What joy filled his heart.
Christianity is real life stuff; and, it aint for the faint-hearted. Welcome to the world of true heroes!