And I also say to you that you are Peter, and on this rock I will build My church, and the gates of Hades shall not prevail against it.
(Mt 16:18 NKJV)

the Lord's church

1. Jesus states that He will build His church upon the facts that Peter had just confessed.  Peter repeats this confession as he preaches Jesus the Christ in Acts 2.   

   “Therefore let all the house of Israel know assuredly that God has made this Jesus, whom you crucified, both Lord and Christ” (Acts 2:36). 

   “Then Peter said to them, “Repent, and let every one of you be baptized in the name of Jesus Christ for the remission of sins; and you shall receive the gift of the Holy Spirit” (Acts 2:38).

   “This Jesus God has raised up, of which we are all witnesses. Therefore being exalted to the right hand of God, and having received from the Father the promise of the Holy Spirit, He poured out this which you now see and hear” (Acts 2:32-33).

2. The future tense ‘I will build’ shows that His church did not come into existence during the Old Testament period.  The church is first spoken of as being in existence in the book of Acts (2:47; 5:11; 8:2).
3. The pronoun ‘My’ reveals that the church belongs to Christ.  We have no right to ‘remodel’ the Lord’s building.  The church must work, worship, and serve according to the pattern provided in the gospel of Christ. 
4. The promise that Hades would not prevail against the church proves that neither His own crucifixion nor the slaughter of His disciples could frustrate His plans.   In fact, the sacrifice of Christ had to occur before He would build His church.  After His announcement in verse 18, Jesus proceeds to prepare His disciples for His death (verses 21-23).  

The Lord promises to save His body (Ephesians 5:23) which is His church (Ephesians 1:22-23).  His gospel never promises salvation to anyone else.

-- Rick Duggin