Why did The Bible of Constantine's era have many Gospels deleted from that of the preceding era?

Answer 1

It didn't. There was no 'Bible' in Constantine's time, it had been canonised by his time, that would take another 50 years or so. The Church had 'Scriptures' which it recognised as having authority as Scripture, and they would be recognised later as The Bible. There were many documents circulating in Constantine's time that the Church had to decide whether or not it should be in the 'canon' of Scripture or not, and the 73 books we now have are the ones the Church agreed were inspired, all others, were not inspired and so not included in Scripture.

AnswerBecause other canons emphasizes on self help, and that would undermine the powers of the early Christian Church.

==new answer== It was so the church leaders could continue to control the people. If there were too many thinkers, their position would be threatened.

AnswerThe New Testament Canon, as we currently have it, has been more or less in place since the end of the second century, when Iraeneus gave a list of the books which were considered canonical at the time. It is true that the canon wasn't finally set in stone until 397, but by that time it had already been in existence for about two hundred years. In Iraeneus's time, the criteria for admitting a gospel or not would have been whether it was of sufficient antiquity, or whether it had appeared on the scene relatively recently.