Instrumental music was commanded in the OT, singing is commanded in the NT (2 Chron 29:25-28, Eph 5:19). The early church understood the command and they only sang. Instrumental music was not added in any type of Christian worship (true or otherwise) until several centuries after the establishment of the Church. Baptism is for the remission of sins (Acts 2:38). Once a person is saved, they can be lost (2 Pet 2:20-21, I Cor 15:1-2, James 5:19-20. Nowhere in scripture do we have any command or example of someone accepting Christ into their heart or being told to only believe or say a "sinner's prayer". Many sincere people, who call Jesus their Lord, who work for Him and that believe in Him will be lost (Matt 7:21ff). The Lord's supper was observed the first day of every week in the first century church which is in agreement with scriptures.

The time will come when people will seek out teachers that will tell them what they want to hear, and will turn their ears away from the truth and will turn to fables (2 Tim 4:3-4).

God is to be worshipped in truth, and truth only comes from God's word (Jn 4:23-24, 17:17).