Baptism is a sacrament of the new testament, ordained by Jesus Christ, … for the solemn admission of the party baptized into the visible church
via Confession of Faith.
The visible church, which is also catholic or universal under the gospel (not confined to one nation, as before under the law), consists of all those throughout the world that profess the true religion; and of their children: and is the kingdom of the Lord Jesus Christ, the house and family of God, out of which there is no ordinary possibility of salvation.
via Confession of Faith.
Why is it important to affirm that all the baptized are thereby admitted into the Kingdom and Family of God and Christ? Because all should be encouraged to trust in their king and father for protection and forgiveness and all must be encouraged to never abandon those precious promises.
Thus, the writer of the letter to the Hebrews encourages readers to see that their tribulations are further proof of their identity as God’s children:
Consider him who endured from sinners such hostility against himself, so that you may not grow weary or fainthearted. In your struggle against sin you have not yet resisted to the point of shedding your blood. And have you forgotten the exhortation that addresses you as sons:
“My son, do not regard lightly the discipline of the Lord
nor be weary when reproved by him.
For the Lord disciplines the one he loves,
and chastises every son whom he receives.”It is for discipline that you have to endure. God is treating you as sons. For what son is there whom his father does not discipline? If you are left without discipline, in which all have participated, then you are illegitimate children and not sons. Besides this, we have had earthly fathers who disciplined us and we respected them. Shall we not much more be subject to the Father of spirits and live? For they disciplined us for a short time as it seemed best to them, but he disciplines us for our good, that we may share his holiness. For the moment all discipline seems painful rather than pleasant, but later it yields the peaceful fruit of righteousness to those who have been trained by it.
Therefore lift your drooping hands and strengthen your weak knees, and make straight paths for your feet, so that what is lame may not be put out of joint but rather be healed. Strive for peace with everyone, and for the holiness without which no one will see the Lord. See to it that no one fails to obtain the grace of God; that no “root of bitterness” springs up and causes trouble, and by it many become defiled; that no one is sexually immoral or unholy like Esau, who sold his birthright for a single meal. For you know that afterward, when he desired to inherit the blessing, he was rejected, for he found no chance to repent, though he sought it with tears.
So they are all sons. Really, the author of Hebrew is just restating a point that he made early in chapter 3 and is then alluded to later in chapter 10:
Take care, brothers, lest there be in any of you an evil, unbelieving heart, leading you to fall away from the living God. But exhort one another every day, as long as it is called “today,” that none of you may be hardened by the deceitfulness of sin. For we have come to share in Christ, if indeed we hold our original confidence firm to the end.
Therefore, brothers, since we have confidence to enter the holy places by the blood of Jesus, by the new and living way that he opened for us through the curtain, that is, through his flesh, and since we have a great priest over the house of God, let us draw near with a true heart in full assurance of faith, with our hearts sprinkled clean from an evil conscience and our bodies washed with pure water. Let us hold fast the confession of our hope without wavering, for he who promised is faithful. And let us consider how to stir up one another to love and good works, not neglecting to meet together, as is the habit of some, but encouraging one another, and all the more as you see the Day drawing near.
For if we go on sinning deliberately after receiving the knowledge of the truth, there no longer remains a sacrifice for sins, but a fearful expectation of judgment, and a fury of fire that will consume the adversaries. Anyone who has set aside the law of Moses dies without mercy on the evidence of two or three witnesses. How much worse punishment, do you think, will be deserved by the one who has trampled underfoot the Son of God, and has profaned the blood of the covenant by which he was sanctified, and has outraged the Spirit of grace? For we know him who said, “Vengeance is mine; I will repay.” And again, “The Lord will judge his people.” It is a fearful thing to fall into the hands of the living God.
But recall the former days when, after you were enlightened, you endured a hard struggle with sufferings, sometimes being publicly exposed to reproach and affliction, and sometimes being partners with those so treated. For you had compassion on those in prison, and you joyfully accepted the plundering of your property, since you knew that you yourselves had a better possession and an abiding one. Therefore do not throw away your confidence, which has a great reward. For you have need of endurance, so that when you have done the will of God you may receive what is promised.
In some circles, it seems the only confidence one is permitted to give people is a confidence that they need never fear any of God’s warnings. But that is far removed from the Bible. A confidence that leads you to no care about the Bible’s warnings, to insist they must be for someone else, is called unbelief.
Read what Presbyterian theologian Charles Hodge had to say:
Wherefore let him that thinketh he standeth take heed lest he fall (First Corinthians 10.12).
…There is perpetual danger of falling. No degree of progress we may have already made, no amount of privileges which we may have enjoyed, can justify the want of caution. Let him that thinketh he standeth, that is, let him who thinks himself secure. This may refer either to security of salvation, or against the power of temptation. The two are very different, and rest generally on different grounds. False security of salvation commonly rests on the ground of our belonging to a privileged body (the church), or to a privileged class (the elect). Both are equally fallacious. Neither the members of the church nor the elect can be saved unless they persevere in holiness; and they cannot persevere in holiness without continual watchfulness and effort. False security as to our power to resist temptation rests on an overweening self-confidence in our own strength. None are so liable to fall as they who, thinking themselves strong, heedlessly run into temptation (p. 181, Banner of Truth, emphasis added).
RELATED:
Can the unregenerate be part of the body of Christ? Can the unregenerate baptize?