The bible states that the Holy Spirit comes to all believers and indwells/seals them, and that happens at the exact time they place faith in Christ and are saved by grace of God!
This statement is correct and scriptural.
ONLY thing needed to do is for a sinner to receive jesus by faith!
This statement is correct, but this is not what any Calvinist believes can happen. A Calvinist does not believe a sinner who is spiritually dead has the ability to be willing to receive Christ by faith. You believe that a person must be regenerated before he has the ability to receive Jesus by faith.
So, your statement contradicts your own doctrine, unless you believe a person can be both regenerated and a sinner at the same time.
Is that what you believe? That a sinner can be regenerated?
And ONLY those saved by God will be able to then Obey God and resist the devil etc, as while yet sinners have no power nor inclination to really do either!
The story of Cornelius refutes this. He believed in God, but he had neither the Holy Spirit, nor was he saved. He was obedient to God, he prayed constantly and gave alms to the poor. God heard his prayers and respected his offerings and sent an angel to tell him to send for Peter. Only after he obeyed (which Calvinists believe is impossible for an unregenerate man) and sent for Peter did he hear the gospel, believe it, and receive the Holy Spirit.
If a man without the Holy Spirit is compelled to sin, then Cornelius would not have been able to fear God and obey him. The scriptures are absolutely clear that he did.
Cornelius absolutely refutes the Calvinist view.
Nevertheless, until Cornelius received Christ he was a servant to sin. He was still under the law. He was still under the penalty of his sins.
The moment Cornelius believed on Jesus, he was no longer under the law but under grace. He no longer belonged to sin, but now belonged to Jesus. He died with Jesus paying the penalty of sin, and was raised with Jesus to new life.
Being a servant to sin does not mean you are compelled to sin every moment, but it does mean you are sold to sin. It is like when a slave was sold in the marketplace. When you sin, you sell yourself to sin. He now owns you, and his wage is death. This does not mean you must sin, a slave can disobey his master, a slave can run away from his master. Still, the slave belongs to the master.
When you trust Christ you are sold to Christ. You no longer belong to sin, you belong to Jesus. Jesus's gift is righteousness and eternal life to those whom he has purchased.