The Greek eisodos means entrance, coming, or access. Paul uses it in 1 Thessalonians 1:9 of his initial arrival among them: 'For they themselves report what kind of reception you gave us. They tell how you turned to God from idols.' In 1 Thessalonians 2:1 he refers to his eisodos as not having been in vain. In Hebrews 10:19, the 'new and living way' is the eisodos into the Most Holy Place opened by Christ's blood.
The eisodos of Hebrews 10:19 is theologically decisive: believers have a bold entry-right into God's presence that the entire Levitical system could not provide. The high priest entered once a year, behind a veil, with blood not his own. Now, through Christ's torn flesh (the veil โ Hebrews 10:20), the eisodos is permanent, confident, and open to all. Paul's pastoral eisodos into Thessalonica (1 Thessalonians 2:1) was meant to model the same gospel-boldness: coming in not with timidity but with Spirit-empowered proclamation. The messenger's entry mirrors the Lord's entry through the veil.