The greatest warning of deception given in God's word would be the single chapter found in the book of Jude. I can honestly tell you that in 55 years of life I cannot remember ever hearing one Pastor teach on the warnings portion of this chapter. The worst attack against the true doctrine of Christ will come from these men mentioned in the book of Jude. If you fail to see their deception, the the doorway to corrupt doctrine can be opened in your life.
Preach the word; be instant in season, out of season; REPROVE, REBUKE, EXHORT with all long suffering and doctrine. For the time will come when they will not endure sound doctrine; but after their own lusts shall they heap to themselves teachers, having itching ears; And they shall turn away their ears from the truth, and shall be turned unto fables. But watch thou in all things, endure afflictions, do the work of an evangelist, make full proof of thy ministry.
James 17-18 tells us that the flesh lusteth against the Spirit, and the Spirit against the flesh: and these are contrary the one to the other: so that ye cannot do the things that ye would. But if ye be led of the Spirit, ye are not under the law.
I've heard it said that the benefit far outweighs the cost. but when your gainful compromise places debt on the strength of the Spirit, can you afford the spiritual battle lost to the flesh?
The definition of ON is: physically in contact with and supported by.
While IN means: expressing the situation of something that is or appears to be enclosed or surrounded by something else.
In John 7:38 Jesus said," He that believeth ON me, as the scripture hath said, out of his belly shall flow rivers of living water.
Acts 16:31 reads And they said, Believe ON the Lord Jesus Christ, and thou shalt be saved, and thy house. Trusting something to be around you is one thing, but trusted that it is the foundation that holds you up is another.
James 4:1-4 From whence come wars and fighting among you? come they not hence, even of your lusts that war in your members? Ye lust, and have not: ye kill, and desire to have, and cannot obtain: ye fight and war, yet ye have not, because ye ask not. Ye ask, and receive not, because ye ask amiss, that ye may consume it upon your lusts. Ye adulterers and adulteresses, know ye not that the friendship of the world is enmity with God? whosoever therefore will be a friend of the world is the enemy of God.
The concept of walking in the kingdom requires that we first recognize that the kingdom is not of this world but of the spirit. Galatians 5:22-26 says
But the fruit of the Spirit is love, joy, peace, long suffering, gentleness, goodness, faith, Meekness, temperance: against such there is no law. And they that are Christ's have crucified the flesh with the affections and lusts. If we live in the Spirit, let us also walk in the Spirit. Let us not be desirous of vain glory, provoking one another, envying one another. When we reach this point we live in a place where the sovereign Lord and ruler is the God of all creation; and we shall know Him by the mercies He's granted in the works of Christ Jesus.