Professing Christians thought that Christ died for the sins of all men on earth. They're even thinking that by just calling the name of Christ, repenting for their sins and accepting Christ as their personal savior is enough, so that their sins will be forgiven and they will attain the salvation promised by God.
However, is it true according to the Bible that Christ gave His life for all the people on earth? In Ephesians 5:25, Apostle clearly stated that Christ gave His life for the Church.
25 Husbands, love your wives, just as Christ also loved the church and gave Himself for her, (Ephesians 5:25, NKJV)
Christ's offered His life not for all men on earth but only for His Church. Why? Why did Christ gave His life for His Church? This is to purchase His Church with His own blood.
28 Therefore take heed to yourselves and to all the flock, among which the Holy Spirit has made you overseers, to shepherd the church of God which He purchased with His own blood. (Acts 20:28, ibid)
Is it really important for Christ to die for the Church and purchase His Church with His own blood? Yes, because it is His way of delivering men from sins and saving them from the wrath of God. Remember that without shedding of blood there is no forgiveness.
22In fact, the law requires that nearly everything be cleansed with blood, and without the shedding of blood there is no forgiveness. (Hebrews 9:22, NIV)
And men can only attain redemption by the blood of Christ.
7In him we have redemption through his blood, the forgiveness of sins, in accordance with the riches of God's grace (Ephesians 1:7, ibid)
And because of this truth, what did Christ told us to do so that our sins will be forgiven and we'll be saved on the day of Judgment? Christ said, anyone enters by Him will be saved. In other words, we should enter Christ so that we will be saved.
9 I am the door. If anyone enters by Me, he will be saved, and will go in and out and find pasture. (John 10:9, ibid)
And those who will enter Christ will become parts of His body.
27 Now you are the body of Christ, and members individually. (I Corinthians 12:27, ibid)
The body of Christ is His Church.
18 And He is the head of the body, the church, who is the beginning, the firstborn from the dead, that in all things He may have the preeminence. (Colossians 1:18, ibid)
It is the Church of Christ and its members are called not Catholics, nor Protestants nor any professing Christians but they are Churches of Christ.
16 Greet one another with a holy kiss. The[a] churches of Christ greet you. (Romans 16:16, ibid)
Therefore, it is important for men to enter or join the true Church of Christ, so that their sins will be forgiven and for them to be saved on judgment day.