Jesus told his disciples that he will return only once and that when he does, after a time of great tribulation, it will be visible to everyone and be followed by immediate and dire consequences for those unprepared and for those who were adversaries of God.
A look at the bible Students and different Jehovah's Witnesses regulations or prescriptions and rules for undergoing baptism.
Always there have been real followers of Jesus who only worshipped his One God, the God of Israel. Many centuries they worked and preached behind closed doors, avoiding persecution and death on the balefire. In fear of the stake for centuries the real followers of God baptised people in their faith, not demanding to be part of one or another church but being part of the Body of Christ.
Often a lot of people do not know to differentiate between Christendom, Christianity, religiosity and even limit religiousness to Christians, forgetting that there are many other religious groups who have all sorts of worship.
Christianity is a love affair. Each person calling himself or herself a Christian should live a life of service to God and Jesus, by serving each other, putting the needs of others before our needs, showing to others the love Jesus gave us.