"And we know that the Son of God is come, and hath given us an understanding, that we may know Him that is true, and we are in Him that is true, even in His Son Jesus Christ. This is the true God, and eternal life." 1 John 5:20
God has come to us in the person of Jesus Christ and given to us understanding, that way we can know Him that is true. And knowing Him that is true causes us to abide in Him and He in us throughout all eternity.
I talk to many people that claim to be a Christian. And there's nothing wrong with claiming to be a Christian. Many people tell me about their relationship with Jesus as if Jesus was in a distant land, not participating in our daily lives; a figure head, but not a living spirit actively participating in the daily affairs of mankind.
Many people tell me that they are a Christian, but no mention of personal relationship, speaking to and hearing from God, co-creating with God so that the purposes of God will come to pass, not just in spite of us, but through us and by us, in cooperation with the express will and active participation of Christ in our daily lives.
Jesus isn't a figure head at all. Jesus is our All in All. And if you are one of those people that have a cursory understanding of who Jesus is, what Jesus has done for you and what Jesus is doing for you right now, today, then you are not abiding in and by the teaching of Christ in the scripture. Even if you want a distant relationship that only acknowledges the once existent Christ, you have to do so by denying the truth of the same scriptures that teach a different philosophy. In other words, if you are satisfied with a understanding that Jesus once lived and He was the/a Messiah, you are in perfect agreement with the Muslims. But the scriptures teach about a Jesus that not only once lived and was the Son of God, but a Jesus that lives and is the Son of God and more. Jesus offers continuing education in spiritual matters by being personally involved in the whole of your life. There is nothing you do that Jesus does not know aforehand. Doesn't it make sense to make an attempt to have a better relationship with Jesus than a simple knowledge that He once existed?
Jesus gives you understanding in equal proportion to you receiving it. Jesus will not give you information that is not wanted, nor will Jesus hold personal seminars with those who can't even find the time to thank Him for all that He has done and all that they already have. Knowing Jesus in the way that the scriptures portray Him and learning about how Jesus interacts with you today, through the scriptures, is a goal that everyone that names the name of Jesus should strive for and encounter.
Jesus doesn't make it hard and Jesus doesn't charge for His services, but you have got to ask to get answers, seek to find and knock to have the door opened. Jesus gives you understanding that you may know Him, now, today. Christianity was made for use for the living, not the dead.