Being disqualified means losing your salvation and not going to heaven. It is not like once you're saved you're always saved, you need to remain faithful till the end in order to stay saved. ( Matthew 24:13, Revelation 2:10).
Just because one enters the Olympic race does not guarantee he will finish the race much less win the race. Likewise, just becoming a Christian does not guarantee he will finish the race and win. Faith only/OSAS does not even fit the analogy Paul made of the earthly race or Christian race, for these two man-made concepts tries to get one finishing and winning the race (salvation) just because he enters the race (becomes a Christians).
The Christian race involves running and some things that running involves:
-- a continued walking in the light so the Christian's sins can be continually cleansed away, 1 Jn 1:7
-- carry out the great commission Mt 28:19,20
-- do good works God ordained Christians are to walk in Eph 2:10 and will be judged by those works, Mt 25
-- be a true worshipper, Jn 4:23,24
-- exhort and encourage, love one another, confess one to another, Heb 3:13; 1 Jn 4:20,21; 1 Jn 1:9
One can enter the race by becoming a Christian, but if he does not run that race by doing the things listed above then he will not finish nor win the race but fall short (Heb 4:1) becoming a reprobate being out of the faith and Christ not in him.