Acts 9:26

And when he was come to Jerusalem, he assayed to join himself to the disciples: and they were all afraid of him, not believing that he was a disciple.

Dummelow thought it strange "that after his arduous work in Damascus, the church of Jerusalem should still doubt the fact of Paul's conversion";[25] but it was doubtless due to the lack of adequate communications in those days, and also to the reluctance of those Christians whose loved ones and friends had been imprisoned, scourged, and even put to death by Saul of Tarsus, to believe that his conversion was sincere. The more remarkable thing, it seems to this writer, is that there was found one, the noble Barnabas, who dared to believe it fully and to undertake his recommendation to the whole church.

Assayed to join himself ... As noted earlier, such an expression as this makes "joining the church" a legitimate concept, provided the uniting with a given congregation is understood by it.