This is pretty lengthy due to all the Scripture in it. I ask you to do your own research also. Do not take my word for it. Be a Berean.
Can a person lose their salvation? Let the Scriptures speak.
Mat 10:21 “And brother shall deliver up brother to death, and a father his child. And children shall rise up against parents and shall put them to death.
Mat 10:22 “And you shall be hated by all for My Name’s sake. But he who shall have endured to the end shall be saved.1 Footnote: 1See 24:13.
Mat 13:5 “And others fell on rocky places, where they did not have much soil, and immediately they sprang up, because they had no depth of soil.
Mat 13:6 “But when the sun was up they were scorched, and because they had no root they withered. Mat 13:20 “And that sown on rocky places, this is he who hears the word and immediately receives it with joy,
Mat 13:21 yet he has no root in himself, but endures for a while, and when tribulation or persecution arises on account of the word, immediately he falls away.
The grace of Elohim works together with man's obedience which then results in steadfast enduring faith or faithfulness.
1Pe 1:22 Now that you have cleansed your lives in obeying the truth through the Spirit to unfeigned brotherly love, love one another fervently with a clean heart,
1Pe 1:23 having been born again – not of corruptible seed, but incorruptible – through the living Word of Elohim, which remains forever,
1Pe 1:24 because “All flesh is as grass, and all the esteem of man as the flower of the grass. The grass withers, and its flower falls away,
1Pe 1:25 but the Word of Elohim remains forever.”1 And this is the Word, announced as Good News to you. Footnote: 1Isa. 40:6-8.
1Pe 2:1 Having put aside, then, all evil, and all deceit, and hypocrisies, and envyings, and all evil words,
1Pe 2:2 as newborn babes, desire the unadulterated milk of the Word, in order that you grow by it,
1Pe 2:3 if indeed you have tasted that the Master is good.
1Pe 2:4 Drawing near to Him, a living Stone – rejected indeed by men, but chosen by Elohim and precious –
1Pe 2:5 you also, as living stones, are being built up, a spiritual house, a set-apart priesthood, to offer up spiritual slaughter offerings acceptable to Elohim through יהושע Messiah.
1Pe 2:6 Because it is contained in the Scripture, “See, I lay in Tsiyon a chief corner-stone, chosen, precious, and he who believes on Him shall by no means be put to shame.”1 Footnote: 1Isa. 28:16.
1Pe 2:7 This preciousness, then, is for you who believe; but to those who are disobedient, “The stone which the builders rejected has become the chief corner-stone,”1 Footnote: 1Ps. 118:22.
1Pe 2:8 and “A stone of stumbling and a rock that makes for falling,”1 who stumble because they are disobedient2 to the Word, to which they also were appointed. Footnotes: 1Isa. 8:14. 2See John 3:36, Heb. 3:18.
1Pe 2:9 But you are a chosen race, a royal priesthood, a set-apart nation, a people for a possession, that you should proclaim the praises of Him who called you out of darkness into His marvellous light,
1Pe 2:10 who once were not a people, but now the people of Elohim; who had not obtained compassion, but now obtained compassion.
Purified through obedience 1:22
1Jn 5:1 Everyone who believes that יהושע is the Messiah has been born of Elohim, and everyone who loves the One bringing forth also loves the one having been born of Him.
1Jn 5:2 By this we know that we love the children of Elohim, when we love Elohim and guard His commands.
1Jn 5:3 For this is the love for Elohim, that we guard His commands,1 and His commands are not heavy, Footnote: 1See 5:2, 2 John v. 6, John 14:15.
1Jn 5:4 because everyone having been born of Elohim overcomes the world. And this is the overcoming that has overcome the world: our belief.
1Jn 5:5 Who is the one who overcomes the world but he who believes that יהושע is the Son of Elohim?
Obedience to His Commands or instructions is the proof of the love we have for Elohim.
om 2:6 who “shall render to each one according to his works”:1 Footnote: 1Matt. 16:27.
Rom 2:7 everlasting life to those who by persistence in good work seek for esteem, and respect, and incorruptibility;
Rom 2:8 but wrath and displeasure to those who are self-seeking and do not obey the truth, but obey unrighteousness;
Rom 2:9 affliction and distress on every human being working what is evil, of the Yehuḏite first, and also of the Greek;
Rom 2:10 but esteem, respect, and peace to everyone working what is good, to the Yehuḏite first and also to the Greek.
Rom 2:11 For there is no partiality with Elohim.
Rom 2:12 For as many as sinned without Torah shall also perish without Torah, and as many as sinned in the Torah shall be judged by the Torah.
Rom 2:13 For not the hearers of the Torah are righteous in the sight of Elohim, but the doers of the law1 shall be declared right. Footnote: 1Mt. 7:21-27, James 2:14-24.
Jas 2:16 but one of you says to them, “Go in peace, be warmed and be filled,” but you do not give them the bodily needs, what use is it?
Jas 2:17 So also belief, if it does not have works, is in itself dead.
Jas 2:18 But someone might say, “You have belief, and I have works.” Show me your belief without your works, and I shall show you my belief by my works.
Jas 2:19 You believe that Elohim is one. You do well. The demons also believe – and shudder!
Jas 2:20 But do you wish to know, O foolish man, that the belief without the works is dead?
Jas 2:21 Was not Aḇraham our father declared right by works when he offered Yitsḥaq his son on the altar?
Jas 2:22 Do you see that the belief was working with his works, and by the works the belief was perfected?
Jas 2:23 And the Scripture was filled which says, “Aḇraham believed Elohim, and it was reckoned to him for righteousness.” And he was called, “Elohim’s friend.”
Jas 2:24 You see, then, that a man is declared right by works, and not by belief alone.
Jas 2:25 In the same way, was not Raḥaḇ the whore also declared right by works when she received the messengers and sent them out another way?
Jas 2:26 For as the body without the spirit is dead, so also the belief is dead without the works.
Luk 14:28 “For who of you, wishing to build a tower, does not sit down first and count the cost, whether he has enough to complete it?
Luk 14:29 “Otherwise, when he has laid the foundation, and is unable to finish it, all who see it begin to mock him,
Luk 14:30 saying, ‘This man began to build and was unable to finish.’
One of the words we see over and over is that of Keep. Or guard, hold firm, attend carefully. We see this over and over again in Deuteronomy. The Hebrew word picture is that of Guarding to keep with all of ones might or power. Grasping firmly.
Joh 15:14 “You are My friends if you do whatever I command you.
Joh 14:15 “If you love Me, you shall guard My commands.1 Footnote: 1See Ex. 20:6, vv. 21&23, 1 John 5:2-3, 2 John v. 6.
Heb 2:1 Because of this we have to pay more attention to what we have heard, lest we drift away.
Heb 2:2 For if the word spoken through messengers proved to be firm, and every transgression and disobedience received a right reward,
Heb 2:3 how shall we escape if we neglect so great a deliverance, which first began to be spoken by the Master, and was confirmed to us by those that heard,
Grace through faithfulness. Yes faithfulness. The English understanding of the word faith is a passive understanding. In the Greek and Hebrew Faith is active. So it would be better translated as faithfulness. We also see we need to add to our faith...Make an effort to enter the narrow gate. We need to guard our hearts...
Looking at Lk 8:21 and 6:46-49 we are reminded to dig deep foundations. The deep foundation is that of Torah or Yahweh Elohim's instructions for His set-apart people.
Looking at Eph 2:8-9 we need to read the whole context. We cannot stop at verse 9.
Eph 2:8 For by favour you have been saved, through belief, and that not of yourselves, it is the gift of Elohim,
Eph 2:9 it is not by works, so that no one should boast.
Eph 2:10 For we are His workmanship, created in Messiah יהושע unto good works, which Elohim prepared beforehand that we should walk in them.
So true salvation is the WORK of faithfulness. The Word of Elohim working in you as you Receive, obey and put into practice that which you have received. I will go into some of the arguments that are used for eternal security another time. For now this is pretty lengthy. Or you yourselves can look those things up and be sure to look carefully at the context in which they are in.