In 1 Thessalonians 4:17, who does 'we who are alive and remain' refer to?

The phrase refers to believers, the church, including the apostle Paul himself, not unbelievers. In the rapture of the church, they are the ones alive and remaining who will be caught up together with the other believers in the clouds to meet the Lord in the air.

Les explains that in 1 Thessalonians 4:17 the pronoun “we” includes Paul with other believers, never the unbeliever. The verse describes the rapture of the church, when believers who are alive and remain are caught up together with them—the other believers—in the clouds to meet the Lord in the air, and so shall ever be with the Lord. By contrast, chapter 5 presents the other side: the unbelieving world, those not caught up to meet the Lord in the air, for whom the day of the Lord comes as a thief in the night in wrath and judgment.

1 Thessalonians 4:17

Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord.

What is the rapture of the church according to 1 Thessalonians 4?

According to 1 Thessalonians 4:17, the rapture of the church is the catching up of living believers together with other believers in the clouds to meet the Lord in the air. The pronouns 'we' and 'us' include Paul and believers, not unbelievers, and so they will ever be with the Lord.