John Calvin Commentary 1 Thessalonians 5:1

"But concerning the times and the seasons, brethren, ye have no need that aught be written unto you." — 1 Thessalonians 5:1 (ASV)

But as to times. He now, in the third place, calls them back from a curious and unprofitable inquiry regarding times, but in the meantime admonishes them to be constantly in a state of preparation for receiving Christ. He speaks, however, by way of anticipation, saying that they have no need for him to write about those things which the curious desire to know.

For it is evidence of excessive incredulity not to believe what the Lord foretells, unless he marks out the day by certain circumstances and, as it were, points it out with his finger. Since, therefore, those who require that moments of time should be marked out for them waver between doubtful opinions, as if they would draw a conjecture from some plausible demonstration, he accordingly says that discussions of this nature are not necessary for the pious.

There is also another reason — that believers do not desire to know more than they are permitted to learn in God’s school. Now Christ designed that the day of his coming should be hidden from us, so that, being in suspense, we might be, as it were, on watch.