There are not two foundations but two aspects of the one foundation.
1. The Church is a mixed body.
– 2:20. This refers to the mixed nature of the Church. Today there are something like 2.4 billion people in the world who identify as Christians in some way. Not all are Christians. One would not abandon a great house because it had a garbage bin.
– Matthew 13:36-43; Acts 20:29-30. Calvin: ‘Thus, although we might dearly wish that everything in God’s church was pure and above reproach, we must nevertheless concede that scandals will arise and that there will be much confusion.’
2. The Lord knows His own.
– 2:19. The firm foundation is singular but it has two aspects.
– Numbers 16:1-5; John 10:14; 1 Kings 19:14, 18. There are secular reports even this week (September 2020) of over a million Christian converts in Iran. Recall 2 Tim. 1:9.
3. Christians depart from iniquity.
– 2:19b; see Num. 16:26. The false believer has no interest in departing from sin. Paul applies this truth in verse 21.
– cleanse yourself; be set apart as holy; be useful; be ready for every good work. These are all descriptions of those in the true church, those who are known by the Lord as His own. – like 2 Peter 5-7, 10.
Watch the service below: