WHEN GOD'S SUCCOUR comes, and victory,
and thou seest people enter God's religion1 in hosts,
extol thy Sustainer's limitless glory, and praise Him, and seek His forgiveness: for, behold, He is ever an acceptor of repentance.2
I.e., the religion of self-surrender to God: cf. 3:19 - "the only [true] religion in the sight of God is [man's] self-surrender unto Him".
Implying that even if people should embrace the true religion in great numbers, a believer ought not to grow self-complacent but should, rather, become more humble and more conscious of his own failings. Moreover, the Prophet is reported to have said, "Behold, people have entered God's religion in hosts - and in time they will leave it in hosts" (Ibn Hanbal, on the authority of Jabir ibn 'Abd Allah; a similar Tradition, on the authority of Abu Hurayrah, is found in the Mustadrak).