Beside possessing the spirit of God within me and knowing it, here's a little more Bible Study supporting my proof/assurance of salvation that there is only one God and only one born believer, the Son of God who had one, a human sinless nature at least whilst on the earth.
Besides Romans 15:6, John 10:29, 14:28, there is also John 3:16 and 1 Tim 2:5 (and many more words of God) that say there is only one God and it is the Father of Jesus his Son who created him to become the sacrifice for sin and thus the high priest, the actual mercy seat for all true believers so we can partake or share in God’s spirit of Truth. Partially today, and completely in our new realm of immortality. As 1 Tim 2:4 states, it is for us to have/ gain knowledge from the Truth of the one God and our Father - not just merely about Jesus the Christ his Son. Jesus was the human sacrifice and the gateway to our salvation. Jesus is the first born of this new creation that God devised, of past, present and future believers (Romans 8:29, Col 1:15, 18; Heb 1:6; Rev 1:5). Jesus is worthy of worship because he is born of God and the Son that sacrificed his life for all, and the first born of the dead to immortality, as even the angels understand this quite clearly and bow to him, upon his birth, on is cross, at his resurrection and ascension, then and today. This thus glorifies God our Father (Romans 15:6 all over again), the ultimate goal, whilst keeping things in perspective and not making an idol of Jesus Christ as God himself, even though he is our Lord and Leader (of the new creation) and Savior (from death) who has earned the right to become the power of God, his Father for all in heaven and on earth. All believers shall know this completely in the next life. They shall know the Truth of God as Jesus possesses it and knew it from at least his baptism.
Blessings to all,
APAK