At the moment of salvation, you are a new creation, baptized by the Holy Spirit into the Body of Christ and made eternally secure, in union with Christ forever.

Jesus says:

“I [Jesus] give [you] eternal life, and [you] will never perish, and no one will snatch [you] out of My hand.” (John 10:28, ESV)

There is absolutely nothing anyone can do to sever your eternal relationship with Christ.

"For I am convinced that neither death, nor life, nor angels, nor principalities, nor things present, nor things to come, nor powers, nor height, nor depth, nor any other created thing, will be able to separate us from the love of God, which is in Christ Jesus our Lord." (Romans 8:38-39, NASB)

There is absolutely nothing you can do to lose your eternal salvation . . . not even sin! There is no sin that can cancel the work Christ already accomplished on the cross.

"For He [God] made Him [Jesus Christ] who knew no sin to be sin for us, that we might become the [perfect] righteousness of God in Him." (2 Corinthians 5:21, NKJV, emphasis added)
 
"and He Himself bore our sins in His body on the cross, so that we might die to sin and live to righteousness; for by His wounds you were healed." (1 Peter 2:24, NASB)
 
"In Him we [are having] redemption through His blood, the forgiveness of sins, according to the riches of His grace" (Ephesians 1:7, NKJV, corrected Greek translation)
 
"by canceling the record of debt that stood against us with its legal demands. This he set aside, nailing it to the cross." (Colossians 2:14, ESV)

For if we keep on walking according to the control of the Spirit, we will not be under the control of the flesh.

"I say then: Walk in the Spirit, and you shall not fulfill the lust of the flesh." (Galatians 5:16, NKJV)
 
"Therefore there is now no [eternal] condemnation for those who are in Christ Jesus." (Romans 8:1, NASB, emphasis added)
 
"For the law of the Spirit of life in Christ Jesus has set you free from the law of sin and of death." (Romans 8:2, NRSV)
 
"For what the [Mosaic] law could not do in that it was weak through the flesh, God did by sending His own Son in the likeness of sinful flesh, on account of sin: He condemned sin in the flesh," (Romans 8:3, NKJV, emphasis added)
 
"so that the requirement of the [Mosaic] Law might be fulfilled in us, who do not walk according to the [desire of the] flesh but according to the [desire of the] Spirit." (Romans 8:4, NASB, emphasis added)

"For those who live according to the [desire of the] flesh set their minds on the things of the flesh, but those who live according to the [desire of the] Spirit, the things of the Spirit." (Romans 8:5, NKJV, emphasis added)
 
"For to be carnally minded [out of temporal fellowship with God] is death; but to be spiritually minded [in temporal fellowship with God] is life and peace." (Romans 8:6, KJV, emphasis added)
 
"Because the carnal [human viewpoint] mind is enmity against [hatred toward] God; for it is not subject to [does not obey] the law of God [the desire of the Spirit], nor indeed can be." (Romans 8:7, NKJV, corrected translation)
 
"So then, those who are in the flesh [carnally minded, under the control of the sin nature] cannot please God." (Romans 8:8, NKJV, emphasis added)
 
"However, you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you [and He is, in fact, presently and permanently in you if indeed you have expressed faith alone in Christ alone]. But if anyone does not have the Spirit of Christ, he does not belong to Him [he has not yet expressed faith alone in Christ alone and, therefore, is not yet a part of the royal family of God, the Body of Christ]." (Romans 8:9, NASB, emphasis added)
 
"But if Christ is in you, although the body is dead because of sin, the Spirit is life because of righteousness." (Romans 8:10, ESV)
 
"But if the Spirit of Him who raised Jesus from the dead dwells in you, He who raised Christ from the dead will also give life to your mortal bodies through His Spirit who dwells in you." (Romans 8:11, NKJV)
 
"I have been crucified with Christ; and it is no longer I who live, but Christ lives in me; and the life which I now live in the flesh I live by faith in the Son of God, who loved me and gave Himself up for me. " (Galatians 2:20, NASB)
 
"For we walk by faith, not by sight." (2 Corinthians 5:7, CSB)
 

Read More about Eternal Security