Primer on Eph 2:20

19 So then you are no longer strangers and aliens, but you are fellow citizens with the saints and members of the household of God, 20 built on the foundation of the apostles and prophets, Christ Jesus himself being the cornerstone (Eph 2:19-20).

Cessationists typically appeal to Eph 2:20 to construct the following argument:

i) A foundation is laid first. A foundation is laid once

ii) The apostles (as well as prophets) are the foundation

iii) Hence, apostles (and prophets) came to an end. That foundational stage ceased in the 1C. Apostles are gone. Prophets are gone.

Problem with that argument is that it logically extends to the superstructure. A building is a unit. The superstructure depends on the foundation.

By parity of argument, if the foundation is temporary, then the superstructure is temporary.

Hence, cessationists create a dilemma for themselves:

i) If they say the foundation is still intact, then the apostolic and prophetic offices continue–since they equate the foundation with apostles and prophets. 

ii) If, however, they say the foundation is gone, then the superstructure is gone.

Cessationists can try to evade this implication by tweaking the metaphor. For instance, they may say the effect of laying the foundation persists. 

That, however, does violence to the integrity of the metaphor. The effect of a foundation only persists if the foundation persists. Remove the foundation, and the upper stories collapse. Only an extant foundation has the effect of a foundation. The superstructure can't rest on the effect of a foundation, absent the underlying cause of the effect. 

The basic problem is the starting-point. Cessationists are casting about for a prooftext. Now, what any Christian ought to do is begin by exegeting the text. Every metaphor has limitations. We need to ask what did the author intend the metaphor to illustrate? 

It's my understanding that this is the intended scope of the architectural metaphor in Paul's argument:

i) Paul is illustrating the principle which underlies the unity of Jewish and Gentile Christians.

ii) Gentile Christians aren't like foreigners or resident aliens in ancient Israel. Rather, they are members of the same household.

iii) That's because they share a common foundation. They are built on the same foundation. Apostles, prophets, and Christ jointly form one foundation for the one people of God. 

iv) In addition, Paul is probably exploiting connotations of solidity. They are built on a firm foundation. 

That's a basic motivation for using foundational imagery. A hard level surface ensures the stability (or structure integrity) of the superstructure. 

v) Finally, Paul is making a point about new temple inaugurated eschatology. 

You can find a detailed defense of this interpretation in standard commentaries by scholars like Peter O'Brien and Frank Thielman. 

That delimits the force of the metaphor. 

Cessationists go beyond that to infer other implications. Problem is, when they do that, they not only disregard the intended scope of the metaphor, but they trip themselves up, for by pressing the metaphor in one direction, to prove cessationism, that opens up the metaphor in another direction to prove continuationism. 

It would be best if cessationists retired this text from their arsenal, because it's a double-edged sword. I think the text is neutral on the cessationist/noncessationist debate. Cessationists are far too invested in this text, and it backfires.