Korean-American Christian said in post #4:
. . . we must develop and maintain an active relationship with Jesus Christ as our Savior and Lord.
That's right.
Also, if people don't feel any relationship with Christ/God, even though they consider themselves to be Christians, it could be because they've subconsciously hardened their heart against God because of something bad which happened in their life, such as the death of a loved one, or the divorce of their parents. They could be subconsciously blaming God for letting that bad thing happen, instead of using His power to keep it from happening. If that's the case, they need to pray and ask God to bring to their mind whatever is coming between them and Him (Psalms 139:23-24), and they need to ask Him to help them not to harden their heart against Him (Hebrews 3:15).
If people haven't become Christians yet, all they need to do to become Christians is believe Jesus of Nazareth is the Christ and the human/divine Son of God (John 20:31, John 3:36; 1 John 2:23), and that He suffered and died on the Cross for our sins and rose physically from the dead on the 3rd day (1 Corinthians 15:1-4, Luke 24:39,46-47, Matthew 20:19, Matthew 26:28).
After people become Christians, to help develop and keep up their relationship with God, they should pray to Him every day, such as with the Lord's Prayer (Matthew 6:9-13), praising and worshipping Him (Revelation 4:11), confessing their sins to Him (1 John 1:9), asking Him for what they need today (Luke 11:3), and thanking Him for everything He has given them (Philippians 4:6). And throughout the day they should immediately bring to Him in prayer anything they become worried about (Philippians 4:6-7).
They should also fellowship with other Christians every day (Hebrews 3:13, Hebrews 10:25), at least in some fashion (Matthew 18:20), such as on this forum, being exhorted by them and exhorting them in turn (Hebrews 3:13).
They also need to examine themselves to make sure they're truly in the Christian faith (2 Corinthians 13:5, Proverbs 28:26, Proverbs 14:12). The way to do this is to read every word of the Bible (Hebrews 4:12, Matthew 4:4) and see if they accept everything it teaches came from God (John 8:47; 2 Timothy 3:16). For just as true Christian faith will initially come from reading (or hearing) what the Bible teaches (Romans 10:17; 2 Timothy 3:15), so people can know they're remaining in the true Christian faith if they continue to believe everything the Bible teaches came from God (John 8:31b; 2 Timothy 4:2-4; 1 Timothy 4:1, Mark 8:35-38).
In order to have any real relationship with Jesus, and God the Father, and the Holy Spirit (Matthew 28:19), most importantly people must believe the right things about Jesus (John 14:6-7): that He's God the Word made flesh (John 1:1,14), that He's the Christ (1 John 5:1; 1 John 2:22), and that He's the only begotten (only born) Son of God (John 3:16,36; 1 John 2:23), meaning He's the only person ever born without any human father (Luke 1:34-35). And people must believe Jesus lived a perfectly sinless life (Hebrews 4:15; 2 Corinthians 5:21) and so could suffer and die on the Cross for our sins and rise from the dead on the 3rd day (1 Corinthians 15:1-4). He rose and will remain forever in an immortal flesh and bones human body (Luke 24:39; 2 John 1:7) as Christians' eternally-human high priest/mediator (1 Timothy 2:5, Hebrews 2:16-17, Hebrews 7:24-26).
Once people come into faith in Jesus Christ, they must obey Him, and God the Father, and the Holy Spirit by repenting from their sins and getting water-immersion (burial) baptized into Jesus (Acts 2:38, Romans 6:3-5, Galatians 3:27). And they must partake of the divine flesh and blood of the bread and wine of Communion (John 6:53, Matthew 26:26-28; 1 Corinthians 10:16; 1 Corinthians 11:27-30). And they should get hands laid on them to receive Holy Spirit baptism (Acts 8:17) and one or more of the Holy Spirit's wonderful Spiritual gifts (Acts 19:6; 1 Corinthians 12:8-10). Then, washed from their sins by water baptism (Acts 22:16) and empowered by the Holy Spirit within them (Acts 1:8, Ephesians 3:16), they must each and every day for the rest of their lives deny themselves, take up their crosses and follow Jesus (Luke 9:23; 2 Corinthians 5:15) by continuing in the faith to the end (Hebrews 3:6,12,14, Hebrews 6:4-8, John 15:6; 2 Timothy 2:12), by repenting from every sin they commit (Hebrews 10:26-29; 1 Corinthians 9:27, Luke 12:45-46) and by doing to the end the particular spiritual works He has given them as individuals to do (Mark 13:34, Romans 12:6-8, Titus 3:8).
But if they as Christians wrongly employ their free will to refuse to do these things, they can't expect to have any continued real relationship with Jesus, and God the Father, and the Holy Spirit. For a continued real relationship with them requires people not only continue to believe in them but also continue to obey them (John 15:10, John 14:21,23). Faith without works is dead (James 2:20) and can't ultimately save people (James 2:14-26, Romans 2:6-8, Matthew 7:21, Hebrews 5:9).