What is the most important question one should ask? Whether he has the spirit of Christ or not! That is the cause of conversion and regeneration; it is the baptism of Spirit. There is no second baptism.
2 Corinthians 6:16 King James Version (KJV)
16 And what agreement hath the temple of God with idols? for ye are the temple of the living God; as God hath said, I will dwell in them, and walk in them; and I will be their God, and they shall be my people.