We should understand that Jesus overcame sin for us by shedding his blood upon the cross. Paul wrote, "Whom God hath set forth to be a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God" (Romans 3:25)
"Finally, my brethren, be strong in the Lord, and in the power of his might. Put on the whole armour of God, that ye may be able to stand against the wiles of the devil. For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places. Wherefore take unto you the whole armour of God, that ye may be able to withstand in the evil day, and having done all, to stand" (Ephesians 6:10-13).
We are not to be ignorant of the devices of Satan; therefore, need to understand the nature of religious spirits. In general, religious spirits are often at work when people use "religion" in defense of their sin.