"He who is not with Me is against Me, and he who does not gather with Me scatters." Luke 11:23
What Jesus was saying is that there is no middle ground. You can't think of yourself or act like a Christian and claim to be right in God's eyes, if you are not truly a Christian. Jesus is also saying.... I don't recognize you as my follower and will not claim you as My own on the last day. Your refusal to accept my teachings is a denial of my teachings, thus you become my adversary.
Acts 11:25-26..."Then Barnabas departed for Tarsus to seek Saul. And when he had found him, he brought him to Antioch. So it was that for a whole year they assembled with the church and taught a great many people. And the disciples were first called Christians in Antioch." Disciple here is a Greek word meaning pupil. In all cases it implies that the person not only accepts the views of the teacher, but that he is also in practice an adherent. This practice of the early church assembling is also noted in Acts 2:42: "And they continued steadfastly in the apostles' doctrine and fellowship, in the breaking of bread, and in prayers." ...and...vs's 46 & 47: "So continuing daily with one accord in the temple, and breaking bread from house to house, they ate their food with gladness and simplicity of heart, praising God and having favor with all the people. And the Lord added to the church daily those who were being saved." At the establishment of the church, when they had traveled from their homes to be at Jerusalem for the observance of Pentecost, (a Jewish feast day), we note that the events of that day resulted in 3000 Jews being saved. Those who were being saved and added to the church, needed to remain at Jerusalem to be taught. So there was a need to provide food and lodging to them while being taught. Verses 44 & 45 tells us how this was accomplished..."Now all who believed were together, and had all things in common, and sold their possessions and goods, and divided them among all, as anyone had need." Notice they were being taught in their assemblies in homes and in the temple. In this case their assemblies were daily. In Acts 20:7 we have example of them meeting on the first day of the week. This is the same pattern we follow today, having an apostolic example of the practice. There would be nothing wrong with meeting every day, as we also have example of that practice, but we recognize both the uniqueness and the urgency of the situation as recorded in Acts 2. As time went on, people left Jerusalem and returned to their homes to establish churches at their locations. The saved of Jerusalem also had to provide for their families, and it is apparent that instruction was given that they should continue to meet and worship, so they returned to their jobs and met as the example in Acts 20:7 tells us they did.
Throughout the book of Acts, we have recorded for us the extreme opposition they encountered from both the government and the Jews. The apostles and anyone else who dared preach the gospel were in constant peril for their lives. Many such men did not fear for their lives and they were responsible for building on the teachings of Jesus with the aid of their helper, the Holy Spirit. Most of them lost their lives for their efforts but gained a far greater reward in Paradise. Satan was beaten back in those days, as we see the gospel message grew exponentially to the point that it was spread throughout the whole civilized world.
We should recognize that though Satan is wounded, he is, like a wounded lion, prowling about seeking who he may devour...1Pe 5:8 "Be sober, be vigilant; because your adversary the devil walks about like a roaring lion, seeking whom he may devour." That raises two questions.
Can anyone defeat such a spiritual adversary?
How does being sober and vigilant help us against such an adversary?
To answer those questions, we should note that Satan's influence was at work in the deaths of all those who died while spreading the gospel. Though this was a hindrance, it also produced a broader field of work for the teachers of God's word. Ac 11:19 "Now those who were scattered after the persecution that arose over Stephen, traveled as far as Phoenicia, Cyprus, and Antioch, preaching the word to no one but the Jews only."
Satan succeeds when he convinces people that they can ignore the sacrifice of God's son and live their lives as though none of those who lost their lives bringing us His word, matters. He persuades people that there is no God and the Bible is the work of a bunch of delusional men, who were merely seeking followers of themselves. He uses men of science to make up any kind of alternative to belief in God, such as evolution, atheism, agnosticism and denominationalism. He uses superstition such as Astrology, palm reading, spiritualists, and many forms of paganism to sway people from following what some consider to be the rigid tenants of Christianity.
God says to put Him first in our lives and such adherence will bring about a great reward on earth and in heaven.
Satan says "Do your own thing". There is no heaven or hell. They are only trying to scare you.
Isaiah wrote, perhaps a thousand years before the death of Christ..."All we like sheep have gone astray; We have turned, every one, to his own way;" (Is. 53:6) Paul quotes the Psalmist in Ro 3:10... As it is written: "There is none righteous, no, not one;" (Ps. 14:3) He continues, after a listing of their foul deeds, to say..."Destruction and misery are in their ways; "There is no fear of God before their eyes." "And the way of peace they have not known." (vs's 16-17) Satan has convinced them, there is no reason to fear God and in so doing, he has succeeded in his work. They are lost.
To be sober and vigilant, God says: "Awake, you who sleep, Arise from the dead, And Christ will give you light." (Eph 5:14) Though Satan is a roaring lion, James says..."Therefore submit to God. Resist the devil and he will flee from you." (James 4:7)