What makes the Christian relationship with God special and unique?
Only Christianity understands God as Trinity. A short answer is that Christian relationship with God is participating in the Trinitarian love within the Godhead, re-produced in our relationship with our neighbors, thus imitating Christ's love to the Father and the Father's love to Christ. We are able to love because we have the Holy Spirit (God himself) dwells in our heart, enabling us to grow in our love disposition. I think only Christianity teaches "God is love", which has a lot of content to unpack from God's revelation of himself in the Bible, through both teaching and works. Works which culminate in Jesus's sacrifice on the cross to heal us out of love and mercy for His creation.
God's love in Christianity is unique in that God himself, who as creator of the universe is powerful and glorious, doesn't find it beneath Him to
- love in weakness that moves the heart, instead of impressing us through force (fire and brimstone). Example: Jesus as lamb of God sacrificed for us on the cross.
- love that searches the lost one sheep in the gutter, instead of requiring us to come to his throne. Example: Jesus brought dignity, not shame, to the repentant regardless of the crime, including the worst offender in 1st century Jewish culture: tax collector (crime against other Jews in colluding with the Romans)
Are people in other religions just having counterfeit, deceitful experiences?
No. Other religions teach love too, but without a model of the perfect love described above, the adherents eventually either idealize a deficient kind of love (such as self-renunciation in Buddhism) or feel something is missing (which hopefully move them to consider Christianity). Other examples of the former:
- In Islam, relationship with God is more characterized as submission
- In Judaism, relationship with God is more of worship and repentance
- In New Age, relationship with God is a personal quest (rather self-centered) where self-giving to others are in the periphery
What about spiritual experience?
In Christianity, spiritual experience is a means to form love in a Christian's heart. It's optional. The primary goal of Christian spiritual experience (while on earth) is not enlightenment, receiving prophecy/knowledge, or seeing the glory of God, but as an aid to help us grow in faith (trust God more) and love (serve God and others out of gratitude in response to God's love for us). Therefore, although other religions have their spiritual experience (genuine or not), if that spiritual experience doesn't lead to Christian love, it does not help one to grow the true relationship with God.
For those Christians who emphasize the "religion vs. relationship" dichotomy, "religion" distracts a person from the true "relationship" with God through Christ, whether it's a Christian religion or other religions. At best, religion should be done only to grow relationship, OR as a response flowing from a true relationship.