Although the Christian Church (all true believers in Christ Jesus) will have been taken to heaven prior to the Tribulation (1 Thessalonians 4:13-17), all witness of Christ Jesus will not have been removed from the earth.

Bibles, other literature, and videos etc., that we Christians use, will be left behind. Most likely, this is how the 144,000 Jews mentioned in (Revelation 7:3-8) will come to a saving faith in the Lord Christ Jesus. It is also believed that the 144,000 Jews will evangelize and draw many to the Lord. They will not be the only ones witnessing for the Lord, however.

As to what is written in (2 Thessalonians 2:7), and the restraining work of the Holy Spirit through the Christian Church at this time, this is not to suggest that the Holy Spirit will not be present upon the earth during the Tribulation. The Holy Spirit is God, and God is everywhere present (omnipresent). God will be active upon the earth controlling events; He will permit, restrain, and bring them about.

(2 Thessalonians 2:7) speaks of a time when the Holy Spirit's restraint of lawlessness through the Christian Church will be removed. When this happens, the world will plunge into lawlessness.