First quit looking how others who call themselves a Christian behave as not all are His own, Matthew 7:21. You said in another thread you have read the Bible cover to cover, but you have no Spiritual understanding as from the Holy Spirit teaching you. A true Christian will be displaying the fruits of the Spirit as they let the light of Christ shine through them, Mathew 5:13-16; Galatians 5:22-24.
You will know you are a true child of God by humbling yourself before the Lord and confessing Him as your Lord and Savior. You believe by faith that He is truly the Son of God, then by being Spiritually reborn again from above you will to see the kingdom of God, John 3:1-7, Romans 10:9,10; Ephesians 2:8-10.
This is the beginning of you having a personal relationship with Jesus as the relationship with Him starts by accepting Him as your Lord and Savior, by prayer (talking to Him and allowing Him to speak to your heart) and through studying the word of God as you pray and ask the Holy Spirit teach you that of what has already been written in the scriptures to learn who Jesus is and your relationship with Him. If you study the book of John this will explain who Jesus is and your relationship with Him.
Again, quit looking at people and put your focus on the Lord as there are many out there that say they are a Christian, but are wolves in sheep clothing wanting to devour you, Matthew 7:15-20.