Jesus taught to see the Kingdom of God you must be born again.
Jesus answered, "I tell you the truth, no one can enter the kingdom of God unless he is born of water and the Spirit. 6 Flesh gives birth to flesh, but the Spirit gives birth to spirit. 7 You should not be surprised at my saying, 'You must be born again.' 8 The wind blows wherever it pleases. You hear its sound, but you cannot tell where it comes from or where it is going. So it is with everyone born of the Spirit” (John 3:5-8NIV).
Jesus was speaking about a spiritual rebirth. When you completely surrender your life to Christ,believing in Him to save you,the Holy Spirit regenerates your spirit. The spirit you were born with comes alive to the Spirit of God. The inner man referred to in the scriptures is your born-again spirit.
“Therefore we do not lose heart, but though our outer man is decaying, yet our inner man is being renewed day by day”(2 Cor 4:16 NAS).
We all are very acquainted with physical birth. Are you aware that all believers in Christ have undergone a rebirth of their spirit? Everyone born on earth must be born again of God’s Spirit to see heaven and understand the things of heaven. Your spirit must come alive to God’s Spirit. Unlike the physical birth the spiritual rebirth is an invisible process. It is inward instead of outward. Most people pay more attention to their outward life rather than their inward life. For the Christian this must change if he or she is to mature in faith, become intimate with the Lord, and live in the Spirit rather than the flesh. A person who moves in the flesh simply thinks contrary to the way God thinks.
Your inner man thrives on the things of the Spirit. It cannot come into agreement with the things of the flesh. The inner man is your spirit born again of God’s Spirit. Your spirit relies on the word of God to feed it. Jesus Christ is the Word. He is the Bread of Life. Daily communion with Christ feeds your inner man. This is how your inner man develops and takes a stronger position in your life. As he grows you become more and more conscious of the Spirit and less and less conscious of the outward life.
“Man does not live on bread alone, but on every word that comes from the mouth of God” (Matt 4:4NIV).
“In the beginning was the Word, and the Word was with God, and the Word was God”
"It is the Spirit who gives life; the flesh profits nothing; the words that I have spoken to you are spirit and are life” (John 6:63 NAS).
If you desire to develop your inward man you must focus more and more on the things of the Spirit. Talk to the Lord and listen for the Lord to speak to you inwardly. Read and meditate on the scriptures daily. Begin to commune with God. Think more and more on the interests of Christ and less and less on your own interests and your spirit man will expand. You will have a greater capacity to understand spiritual things. Your capacity for inward peace will also increase. How do you set your mind on the Spirit? Just begin thinking about the Lord and His goodness and what He accomplished on the cross for you. Begin to praise and thank Him for His blessings in your life. If you are worried about something change the channel of your thoughts to how God will take care of you and supply your needs. A great deal of walking in the Spirit is learning to constantly shift your thinking to the Lord and His marvelous love.
“For those who are according to the flesh set their minds on the things of the flesh, but those who are according to the Spirit, the things of the Spirit. 6 For the mind set on the flesh is death, but the mind set on the Spirit is life and peace, 7 because the mind set on the flesh is hostile toward God; for it does not subject itself to the law of God, for it is not even able to do so; 8 and those who are in the flesh cannot please God. 9 However, you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. But if anyone does not have the Spirit of Christ, he does not belong to Him” (Rom 8:5-10NAS).
Your strength in life comes through the Holy Spirit in your inner man. The quality of your life depends on your inner man. Shift to an inward life rather than an outward life. Inwardly there is always peace. Outwardly peace depends on the happenings around you. The inner man is who you really are in Christ.
“… that He would grant you, according to the riches of His glory, to be strengthened with might through His Spirit in the inner man, 17 that Christ may dwell in your hearts through faith; that you, being rooted and grounded in love, 18 may be able to comprehend with all the saints what is the width and length and depth and height-- 19 to know the love of Christ which passes knowledge; that you may be filled with all the fullness of God. 20 Now to Him who is able to do exceedingly abundantly above all that we ask or think, according to the power that works in us, 21 to Him be glory in the church by Christ Jesus to all generations, forever and ever. Amen”( Eph 3:16-21NKJV).