The clause who bought them presents difficulties for the interpreter. Can those whom Christ has redeemed ever be lost? Did the false teachers lose their salvation? 

救恩可以失去。耶稣付了所有人赎价。

Some commentators assert that "Christ bought them at the tremendous price of his blood to be his own forever." 

当然!

But the fact that the teachers faced swift destruction contradicts this interpretation. 

没有矛盾。作者屁股没做正，预设前提。

 Commenting on this clause, Henry Alford confidently states, "No assertion of universal redemption can be plainer than this." 

绝非普救论

But if Jesus had given these teachers eternal life, they would never have fallen away. Scripture clearly teaches that those people to whom Jesus has given eternal life "shall never perish" (John 10:28; also see Rom. 8:29-30, 32-35; Eph. 1:3-14).

 当然没有永生，仅是重生了而已，没有最终得救。

Although Christ's death was sufficient to redeem the whole world, its efficiency comes to light only in God's chosen people. 

错! 耶稣事实上付了万人赎价。

Were the false teachers recipients of God's saving grace? Apparently not, for they repudiated Christ.

当然收到救恩了! 买都买了，都重生了。

 If we look at the words "denying the sovereign Lord who bought them" in the light of the broader context, we discover a clue. We notice that at one time these false teachers professed the name of Christ, for they said that they knew him and the way of righteousness (2:20-21). They made it known that Jesus had bought them, but they eventually rejected Christ and left the Christian community. As John writes, "They went out from us, but they did not really belong to us" (I John 2:19; and see Heb. 6:4-6; 10:26-29). Hence, their denial of Christ showed that they were not redeemed.    

又是自称基督徒，哈哈! 回主贴找劈去!

他们实际上重生得赎了，有重生的信，但没有持守下去。