Jesus is certainly coming again. This has been a central belief of Christians since Jesus died for our sins on the cross. But some in Thessalonica claimed that Paul had written to them saying that the second coming of Christ had already happened. They said that Jesus' second coming happened when he was raised from the dead. If that were true, he wouldn't be coming again in order to gather his believers to be with him in the kingdom of God.
Paul taught the Thessalonians, "Don't be deceived by this teaching!" Jesus is coming again! Before that happens, there will be a time of tribulation, when the "man of lawlessness" will come and deceive many. In fact, he is already at work, although he has not been revealed. But he is doomed to destruction. When the Lord Jesus returns, he will destroy him.
Those who do not love the Lord will be deceived by the lawless one and will themselves end up being destroyed. But those who belong to the Lord will be saved through destruction by the Lord Jesus so that they might share in his glory.
Application: Father, thank you that Jesus is coming again! Help us to stand firm to the end, in faith
One Word: Don't be deceived; stand firm