Acts 2:42
ESV - 42 And they devoted themselves to the apostles' teaching and the fellowship, to the breaking of bread and the prayers.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
The apostles doctrine was, John 6:47 Believe on the Lord Jesus Christ and thou shalt be saved. Acts 16:31.
John 3:16-18. For God so loved the word, that He gave His only begotten Son, Jesus, that WHOSOEVER, believeth in Him, should not perish, but have everlasting life. Jesus said it, we believe it, and that settles it. We can no longer be condemned.
Jesus paid the penalty for our sin so we would not have to go to hell to pay for them. Romans 6:23 For the wages of sin is death, but the GIFT of God is eternal life, through Jesus Christ our Lord.