Interesting logic, except all translations do not use the word 'disciples'. Some just say, go and 'teach all nations'.
Did you notice this scripture pretty much oozes of 'good works'? How could that be? These people, who were disciples were already boasting of being baptized, and observing the commandments of Jesus. They were also losing their focus on the cross and taking glory away from Jesus. Remember you said that I boasted just bacause I 'climbed' into the baptistry and took away the glory of Jesus for doing these good works. You must hate to read good works scriptures, especially when Jesus tells us to do good works, (and BTW, Jesus did not use the word, 'grace' once).
After saying that, I know we need to keep our eye on the cross, and believe Jesus, and trust in him and his grace, but to ignore the accompanying works that go along with belief, and love, and faith, is not the gospel of Jesus Christ.
Besides, just because you are a disciple, doesn't necessarily mean you are 'saved'. I believe that a person is taught the gospel and then according to Mark 16:16, and Acts 2:38, if they believe and are baptized they 'shall be saved'
'Shall be saved' does not mean they are 'automatically, and immediately saved' then OSAS.
The saving process is a lifelong process of believing in Jesus and observing the things that he has commanded us to observe, and enduring to the end.
And finally when you are resurrected in your perfect body of flesh and bone and spirit, you will come to know that you are saved or not. No automatic pass to eternal life.