Is it more to ask which God a man could be in fellowship with God but if it is not the God of the bible or the Jesus of the bible As Christians we follow Christ which is the Hebrew word for Messiah. Historical Christianity has laid down certain doctrines that define what a Christian is , the bible essentially does .You cannot follow say Allah and be a Christian The bible defines what are God is and the bible defines who Jesus of Nazareth is as he is both fully God and fully man A Christian it is essence has to believe the gospel that Jesus died for our sins and it is by faith we are saved not works. To me there are many movements such as bethel which to me pit themselves outside historical Christianity because of there believes on who Jesus is and like the mormans redefine who Jesus is. When you have read say Walter Martins book on the kingdom of the cults or books on what other faiths such as Islam believe Are beliefs as christians are important When you ask the question can a Christian be in fellowship with God can be a Christian , I ask the question what is the god they believe in , if it is the god laid down in scripture then I would say yes but no otherwise as not believing in God would make you an atheist .
In my understanding, there can’t be fellowship with God without Holy Spirit... so that excludes all those groups, no?
What we define the holy spirit as is also important mormans if you ask them whether mormanism is true ask for a burning in the bosom as we define the nature of the work of the holy spirit as a third person in the trinity and not as a force The biblical definition of what the holy spirit is as there are many spirits out there calling themselves the holy spirit but aren't