Paul made it clear the internal conflicts. And we will be purified of our own evil nature to enter eternity. "All things are purified by fire". No question devil spirits influence our minds and actions. Bringing forth and manifesting evil and sin.
However, when Christ says to Peter: "Get behind me Satan." In your perspective, one must say that Christ is speaking to Satan who has entered into Peter. Satan himself has entered into Peter!!! For you contend that it is devil spirits within man working iniquity. It is agreed that devil spirits do take residence in men. Records of casting out spirits make that clear. However, it appears that you are in error that all men find themselves in such a condition of devil spirits taking up residency.
"Get behind me Satan" spoken to Peter is Christ speaking to Satan himself within Peter? I think not.
Distinction should be made that the influence of devils influence the heart and minds of men. The mind (and therefore the actions) being conditioned into devilish or evil thoughts and actions. In a sense, devils have entered. And yet haven't taken up residence. Thus, when Christ rebuked Peter, he wasn't rebuking a spiritual entity within, but rather devilish thoughts emanating from Satan.
"There is therefore now no comdemnation to them which are in Christ Jesus, who walk not after the flesh, but after the spirit. For the law of the Spirit of life in Christ Jesus hath made me free from the law of sin and death. For what the law could not do , in that is was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh. That the righteuosness of the law might be fulfilled in us, WHO WALK NOT AFTER THE FLESH , BUT AFTER THE SPIRIT."
"This I say then, WALK IN THE SPIRIT, and ye shall not fulfill the lust of the flesh. For the flesh lusts against the spirit and the spirit against the flesh; and these are contrary the one to the other, so that ye cannot do what ye would."
What you miss in your understanding is the power of holy spirit within. "Greater is he that is IN YOU, than he that is IN THE WORLD." This does not say that holy spirit within you is greater than the devil spirits that are within you. It's talking about devil spirits in the world that affect your heart and mind. ( And certainly they will enter in and possess if given access. But, again, this is not the bane of ALL men).
"I beseech you, therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service." [A devil spirit infested body is hardly holy].
How then to accomplish this presentation?
"And be not conformed to this world, but be ye TRANSFORMED by THE RENEWING OF YOUR MIND, that ye may prove what is that good, and acceptable, and PERFECT, will of God."
So, it is a renewing of the mind to truth. Casting out the devilish conformation to evil, worldly thoughts. And walking in the spirit to guide in this endeavor. "Put on the whole armour of God."
There is therefore now no condrmnation…