"And this is eternal life, that they may know You, the only true God, and Jesus Christ whom You have sent" (John 17:3). These words from the prayer of our Lord give us direction for our relationship with God. To say it in another way, eternity is to be taken up with knowing and experiencing God Himself. Of that there will be no end. God has opened the door to us, removing all barriers to fellowship with Himself.
The saints of the Old Testament, under the Old Covenant, were limited in their fellowship with God. Most truths were illustrated by types, and all were in anticipation of the day when the door would be opened and "all would know Him" (Heb. 8:11). This true knowing of God does not begin in heaven, however, as some might think. It began on the day of Pentecost, when the Holy Spirit was given because Jesus had been glorified. God came in the person of the Holy Spirit to dwell in His church. In so doing, He brought the presence of the Father and the Son within the believer (John 14:23).
A fundamental error that is made today is to substitute knowing about God for knowing God. A person may know many true facts about God and believe these facts, and still not know God. Knowing God means experiencing God. In human relationships, you cannot know someone unless you experience involvement with that person. It is the same with God, but experiencing God is much deeper than experiencing another person. God is spirit, God is pure and holy, and God is God. Thus we cannot approach God on a casual basis as we would another person. We come on our knees, with deep reverence in our hearts, but we must come desiring to know God. "Let us therefore come boldly to the throne of grace, that we may obtain mercy and find grace to help in time of need" (Heb. 4:16). If we will come, He is there to meet us.
Another mistake that many have made is to separate salvation from knowing God. Since knowing God seems so difficult and demanding, salvation seems to be often defined as just believing certain true facts. Along with this there may be some repentance. But neither believing facts (James 2:19) nor repentance alone is knowing God. It is true that we must repent of sin and turn to God, but only the faith that is imparted by God to the one who is looking to Him will allow us to receive God into our lives. True faith is born of God, by the word of God spoken to our hearts.
When that word of faith is imparted to us, there must be a response in our hearts of acceptance and belief. Our response of love will be obedience to the word spoken (John 14:23). This in turn will bring "fruit," or evidence. It is impossible to hide faith. In a response of faith, we know and experience God. It is only then that the word of God becomes ours, and Christ is formed in us (Gal. 4:19). This is the only word that can save us (James 1:21).