The city of Philadelphia was the sixth city on the Roman mail route, which originated in Ephesus of Asia, and it lay about 28 miles east and southeast of Sardis and forty miles north and northwest of Laodicea. It was one of two churches for whom Jesus had praise but no specific rebuke. Some folks like to interpret these letters to the seven churches to represent specific eras in church history, rather than see the interpretation in the days of the addressees themselves. I liken such interpretations to newspaper and / or historical eisegesis, because it certainly isn’t exegesis. Absolutely everything that is proposed in those interpretations is purely subjective. Not one word of such interpretations could be objectively supported in Scripture. Nearly, always the eisegesis is held in greater honor than how its original readers understood the writing of its author, thus making the word of God of no effect to modern readers.
Jesus’ letter to the church in Philadelphia departs from his usual means of introduction to the seven churches, in that he doesn’t attach to his person any of the descriptions of himself in Revelation 1:17-20. Instead, Jesus describes himself as “he who is holy, and he who is true…” (Revelation 3:7). I believe that in doing this, Jesus points us to the Old Testament with an emphasis toward understanding what he means by holy and true.
In ancient Israel the altar of sacrifice was ‘most holy’ to the Lord. Anything that touched the altar of sacrifice was holy (Exodus 29:37). When God came down to Moses and touched the ground, the ground became holy, so Moses had to remove his shoes in order to approach God (Exodus 3:5). Moses was holy, i.e. set apart to God, but his shoes were not in that they were used in normal affairs. Therefore, when the Lord created a people for himself by making a covenant with them, he told them to sanctify themselves, i.e. set themselves apart from all other nations and be holy, because the Lord is holy (Leviticus 11:44-45; 20:26).
With this in mind, whenever one of his people gave himself or any of his children to another god, that one defiled the Lord’s sanctuary, because he and his house were already devoted to God. Moreover, he also defiled the name of the Lord. He would be cut off from the nation by God and was to be slain by the people (Leviticus 20:2-3). There is none holy but God (1Samuel 2:2) and whomsoever he chooses to be his own must set themselves apart from all others and devote themselves to the Lord (Leviticus 20:7; Deuteronomy 7:6). Therefore, by Jesus saying he is holy (Revelation 3:1), he is saying that his disciples must set themselves apart for his (Jesus’) pleasure and not allow themselves to be deceived by that Jezebel to eat things sacrificed to idols (cf. Revelation 2:14, 20).
Jesus also claims to be true (G228). Thayer’s Greek Lexicon defines this word as:
“that which has not only the name and resemblance, but the real nature corresponding to the name, in every respect corresponding to the idea signified by the name, real, true genuine; it is opposite to what is fictitious, counterfeit, imaginary, simulated or pretended; it contrasts realities with their semblances; it is opposite to what is imperfect defective, frail, uncertain.”
The fact that Jesus even mentions he is “he who is true” may be a reply to what his detractors had been saying about him in the assembly of believers in Philadelphia. In this context, Jesus’ critics were not true (cf. Genesis 42:11), but spies sent into the church by stealth (cf. Luke 20:20; Galatians 2:4) with molded, prepared words (2Peter 2:3) meant to win over the believers there to another authority (cf. Revelation 2:14, 20), namely, the authorities at Jerusalem. On the other hand, Jesus is true, i.e. his words are true; he is a true witness (Proverbs 14:25; Revelation 1:5; 3:14). He executes true judgment (Ezekiel 18:8), and expects his people to do the same (Zechariah 7:9). We can know him who is true, because we are in him who is true, and he is our true God and our eternal life (1John 5:20).
 Smyrna was the other church.
 Jesus also describes himself as, “he who has the key of David, he opens and no man shuts, he shuts and no man opens,” but I intend to address this in my next study.