The welcoming spirit, is the spirit you allow to enter in that is anything other than the Spirit of God. This spirit is invited in through the acts that are done as thoughts are entertained by an individual. If the Spirit of God is not in control, then the hunger and thirst for being complete is always in play; without a spirit or the Spirit, the soul is incomplete. There is now an attempt to complete or make the soul whole, it welcomes in a "say so". The Spirit of God has the "say so" when it is in control. Now, because the soul wants to be in control, it recognizes that it is in need of the missing link. It takes in a spirit, but not the right spirit. The soul then welcomes in a spirit that is not the Spirit of God. This is why no matter what you do, the ungodly spirit(s) will never do for you or give to you what the Spirit of God can do or give.
Welcoming in a spirit opens the door for other spirits because only the Spirit of God can produce fullness, completeness, or perfection in Christ Jesus. No other spirit can produce the Fruit of the Spirit with nine different fruit juices. (see Galatians 5:22-23) There will never be enough spirits that you allow in that will/can do what the Spirit of God can do. Now you have become a spirit chaser, chasing after spiritual things that can only come from what the Spirit of God can give you.
The spirit that many are welcoming in gladly, is the spirit of the Antichrist. This spirit looks like Christ and sounds like Christ, but it lacks the Spirit of God, therefore it is NOT anointed. This is why one can go against the word of God, but say that they are of God. The spirit of the Antichrist is just as strong, if not stronger than the spirit of Jezebel. The spirit of the Antichrist calls wrong right and will defend it. This welcomed spirit is easily accepted because it allows one to keep their will. When an individual operates in his/her own will, the will of God cannot be present. Two wills cannot and will not operate in the soul. An evil and righteous spirit cannot possess the same vessel. The vessel, ‘aka’ body, is a temple for the Holy Spirit; we must honor it. Therefore, if we are on one accord with God then we are free of sin.
When the spirit of the Antichrist is present it does not mean one cannot prophecy nor speak a word. The bible says in Romans 11 that gifts and his calls are established (final; permanent). So for the many who believe that their leader is anointed, we are told in 1 John 4:1-6:
Beloved, do not believe every spirit, but test the spirits, whether they are of God; because many false prophets have gone out into the world. By this you know the Spirit of God: Every spirit that confesses that Jesus Christ has come in the flesh is of God, and every spirit that does not confess that Jesus Christ has come in the flesh is not of God. And this is the spirit of the Antichrist, which you have heard was coming, and is now already in the world. You are of God, little children, and have overcome them, because He who is in you is greater than he who is in the world. They are of the world. Therefore, they speak as of the world, and the world hears them. We are of God. He who knows God hears us; he who is not of God does not hear us. By this we know the spirit of truth and the spirit of error.
(Note: The underlined verse needs further discussion) It has become a trend for individuals to say they believe in Jesus Christ as being God in flesh. The fact still remains that faith in Jesus is an action not just a statement. When you confess Jesus then you believe He is of God. Having the idea or a belief in Jesus Christ as being the Son of God causes one to take action. As children of God we know that Holy Spirit is in us and we can walk in the ways of God. God receives us because we are of Him, as a result those that are of Him are clean and can obtain the fullness of Him. In conclusion, there is no need to welcome spirits because you allow the Spirit of God to do what it has been put in position to do.