^3:20 `Behold, I stand at the door and knock; if anyone hears My voice and opens the door, I will come in to him, and will dine with him, and he with Me.

Behold, I stand at the door and KNOCK;

This is the door of the church at Laodicea (or your church) and not necessarily the heart's door as so many evangelists use this verse. This would indicate that there either were lots of deaf Christians or lazy Christians ignoring the knocking.

Note, too, that Christ is outside the church (Hebrews 13:12-13). We can go outside the church to be with him individually OR the members of the church can invite Him in to be with them. He would prefer to come inside because He says

if anyone (in the church) hears my voice (knock) and opens the door,

There had to be some life in the church in order to hear the knock and open the door - John 5:24-29 and John 10:24-30. Opening the door is the act of repentance and discarding all fleshly things (Galatians 5:19-21).

I will COME IN to him, and will dine with him, and he with Me.

As we sit down to eat with Him (His word), His Spirit is there as He shares His food (bounteousness of the Father) with us. Then we grow and become strong believers. Thus begins the beautiful relationship between the believer and the Holy Spirit (Colossians 3:15-17). One note of warning: James 5:9 indicates those who don't open the door will face the Judge!