When Christ came, He proclaimed the good news of peace to you who were far away and peace to those who were near. For through Him we both have access by one Spirit to the Father. So then you are no longer foreigners and strangers, but fellow citizens with the saints, and members of God’s household, built on the foundation of the apostles and prophets, with Christ Jesus Himself as the cornerstone. The whole building is being fitted together in Him and is growing into a holy sanctuary in the Lord, in whom you also are being built together for God’s dwelling in the Spirit.
(Ephesians 2:17-22 Holman Christian Standard Bible ® ©)
The assembling that the writer to the Hebrews mentioned in 10:25 was like this, I believe – being built together; not just going to meetings. Being joined in relationships. Loving one another.