Church Decline Reasons

This topic is huge.  Satan and his followers are counting on that, to limit Christian intercessors' effectiveness.  You can see that in the large number of topics addressed in my intercessory prayers.  My prayers are constantly being improved, since Satan engages in flexible response.  If something stops working, he tries numerous other tactics until he finds an effective one his opponent is ignorant of.  Fortunately, I have the Holy Spirit's gift of Word of Knowledge. (You could too, if you asked for it.)

Satan either comes as a roaring lion or as a snake in the grass or as a cloud of mosquitoes, based on which general tactic would be more effective.  Satan hits numerous important targets with seduction, intimidation, blackmail, extortion, spells, charms, idols, tattoos, soul & sex ties, warfare tactics, hypnosis, negative advertising, spies, agents de provocateur, divide-and-conquer, slander, libel, infiltrate-and-subvert, distraction, misleading information, destructive alternatives, etc.  Satan gives attention to the general target with the same, but with less agents and effort. Satan's agents are pumping out demons to the whole planet, governments, corporations, movements (like denominations), religions, etc. Satan is recruiting sick people and compromised people to man these positions.  He is also recruiting misled people to fill his more benign positions without letting them know who their ultimate boss is.

So what in these lists would Satan use against the only religion that potentially has the wisdom and authority of the Holy Spirit that could permanently defeat him?  All of them - and more.  The Christian churches are not teaching the Christians how to effectively walk as Jesus walked, using divine guidance, wisdom and tools (1 John 2:6).  Keep them as docile sheep in the pasture - until Satan roars like a lion.

Ideas to counter it

The Chinese Christians came under attack by Marxist Satanists who wanted to wipe them out.  The big churches were the first to be compromised or destroyed.  The Christians went underground and secretly met in houses, as the book of Acts taught them. Suddenly, the Christians became very fruitful.  More persecution didn't stop them.  The Marxists reopened the big, "official" churches, to get more information on these house churches.  It didn't work, so they threw all the members in jail and re-closed the big churches!  At this point, the Christians in China may be a majority, as they were in the Roman empire of old.  They recently felt safe enough to start building their own big church buildings.  The Marxists finally panicked this year and started smashing these big churches.

The last American Christian denominations to keep growing are the Pentecostal churches, like the Assemblies of God.  They have and use the the gifts of the Holy Spirit.  They are the most spiritually attacked churches, because they are the closest to growing into a threat to the kingdom of Satan.  The other, declining churches need Pentecostal Christians to come spread the word in them.

There are contemporary churches that take off like rockets.  Satan used the schools to stratify the culture by age, to keep the young distant from the older, Christian culture.  Due to the philosophical void of Nihilism and Humanism, these younger strata still need Jesus' churches to adapt to their age groups' culture.  They often are not Pentecostal, so Satan's forces play "whack-a-mole" with the pastors and elders of these churches. They pop up fast and they go down fast. They need defense.

Christian Revivals are not some arcane mystery, coming out of nowhere.  George Otis carefully studied the history of revivals of old and came up with the common principles of them all.  He published these principles - and suddenly revivals broke out all over the world!  This works! His organization is still offering these principles and testimonials.  

North America is the exception to the revivals.  The people there are worshipping money (Matt. 6:24) and nationalism.  When the United States Dollar crashes soon, the American Christians will pray.  Then revival will come.