King is sailing, they say

Quoting from Paul is very difficult.  His sentences are so long that to get a manageable length means dissecting the sentence.  But the most effective passages are those that are in some sort of context.  With that said, consider this passage (beginning mid-sentence, of course):

Colossians 1:22-24

in the body of His flesh through death, to present you holy, and blameless, and above reproach in His sight–if indeed you continue in the faith, grounded and steadfast, and are not moved away from the hope of the gospel which you heard, which was preached to every creature under heaven, of which I, Paul, became a minister.  I now rejoice in my sufferings for you, and fill up in my flesh what is lacking in the afflictions of Christ, for the sake of His body, which is the church, etc etc…   (NKJV)

Hello?  Read that again, I think I missed something.  Paul’s long and convoluted sentences are his greatest strength.  You can sometimes just glaze over them like a confusing legal document without looking at the fine print.  Hmmm I don’t know where to start with the difficulties in this one. 

1) Paul clearly says that we will be presented holy and blameless, but there is an IF statement - a condition.  IF we continue in the faith and are not moved away from the hope of the gospel.  I had that faith and hope for years.  It is disappearing.  Am I no longer holy and blameless?  Am I to lose my salvation?  There are several places in scripture to support this argument, but just as many that oppose it.  This is a debate which has raged for 2000 years, and I will certainly not settle it here. 

2) In Christian circles, the security of salvation is a hot-button issue, but that difference of opinion is something which can be lived with.  Next though, Paul sneaks in a real heresy.  Paul rejoices in his own sufferings because he needs to fill up what Christ’s sufferings did not finish???  eh, come again??  That is clearly the antithesis of orthodoxy.  Jesus’ sacrifice is sufficient to present us holy and blameless - isn’t it?  Is the suffering and death on the cross enough?  Did Paul feel that he needed to suffer further to perfect his own justification?  Could this be an allusion to a sort of martyr’s theology?

Let’s look at that same verse in a couple different versions:

Now I rejoice in what was suffered for you, and I fill up in my flesh what is still lacking in regard to Christ’s afflictions, for the sake of his body, which is the church.   (NIV)

Now I rejoice in my sufferings for your sake, and in my flesh I do my share on behalf of His body, which is the church, in filling up what is lacking in Christ’s afflictions.   (NASB)

I looked at several other translations, and they all read similar.  Seems pretty straightforward to me; Paul says, at the very least, that something is ‘lacking in Christ’s afflictions’.  Either we have Paul describing a blatant heresy, or am I reading this wrong and he is describing something else that is lacking.  Can somebody tell me what that something is?