They go by the calendar- time and events that God goes by. They are our true brothers/sisters/mothers 'in Christ' as we were grafted in. It was a catholic who changed the calendar away from the times/events of God and that lined up perfectly with events such as the Passover. Basically, all the apostles were Messianic as PAUL was - who God used to write over half the NT. What opened his eyes was the Holy Spirit.
Messianics' have the roots of Christianity and teach with a better understanding of the OT which is the shadow of the NT. Praise God for their wonderful teachings and devotion to JESUS alone!
I have loved learning about the calendar of God’s appointed times. Learning about the Passover from messianic jews has been such a comfort. AND it is almost time for Sukkot, after a season of being judged, we see our shelter. The feast of the Tabernacles, the Season of Joy!
http://www.hebrew4christians.com/Holidays/Fall_Holidays/Sukkot/sukkot.html