The key to perfection is: Christ

Before the centurion Cornelius was converted, God had been pleased with his behavior in relation to his people, and as for his interest in knowing it, demonstrated in the offerings he brought to the temple, however, he could not be saved by such works , and for this, he was oriented to receive the apostle Peter in his house so that hearing the gospel he could believe in Christ and be saved.

In several passages of the Old Testament we see the Lord, declaring and calling men to practice what was right, and to keep His commandments.

This shows that they were capable, all of them, of attending to their ordinance, otherwise, they would never have ordered such a thing.

Then there was this justice derived from the Covenant of Works that God had made with Israel, but this justice that was preached by the scribes and Pharisees, the religious of Israel, our Lord Jesus Christ, affirmed that it was insufficient and unfit to give someone access to the Kingdom of heaven.

Because this?

It is not difficult to understand.

First that heaven is a place of absolute perfection, because all its inhabitants are perfect. Perfection in holiness, morally perfect, perfect in everything.

And it is well known that such perfection does not exist in any descendant of Adam, because of sin, because of the sinful nature that exists in every person.

This demanded, on behalf of the Lord, to provide themselves with children perfect for heaven, similar to Christ, that such a nature would be crucified, demolished, dispossessed, so that in its place a new nature created by God, coming from the high heavens, would rule. operated by the Holy Spirit, generating a new birth in those who will inherit heaven.

This is what is meant by the expression uttered by our Lord "that the flesh profits nothing", that is, earthly nature fallen into sin, can not serve God's purpose for man. On the contrary, she opposes him.

And in the same way, "when it says that it is the spirit that vivifies", the meaning here, is that eternal life is generated by the Holy Spirit, making the believer have a new spiritual life, which is apt to fulfill the eternal purpose of God.
Hence, the apostle Paul affirms in Galatians 5, that those who belong to Christ crucified the flesh with their passions, that is, they had their old nature fallen into sin, condemned by God to be crucified together with Christ, so that they can live like their beloved children in newness of life.

In the same way it is affirmed in Romans that those who belong to Christ are no longer in the flesh, but in the Spirit, that is, they are no longer under the absolute government of such fallen nature that was crucified, but under the influence of the Holy Spirit .

Hence the ordinance of the Lord for believers who are perfect just as God is perfect.

And from the apostle Paul, may they be imitators of God as beloved children.

Because having overcome the flesh, earthly nature fallen into sin, through faith in Christ, can now be undertaken on the path of perfection through the sanctification of the Holy Spirit, until they are found in heavenly glory in absolute perfection, according to them it will be granted by the Lord.