What does 1 Timothy 4v10 mean?  

For therefore we both labour and suffer reproach, because we trust in the living God, who is the Saviour of all men, specially of those that believe.

We have two erroneous interpretations of this passage.  First,  the universalists will argue that all men will be saved as Christ is the Saviour of all men.  Second, Calvinists teach that it means that Christ is the "Saviour" of all men in that he is the temporary provider and sustainer of them.  However, consistency requires us to interpret the word "Saviour" in the same way that it does in chapter 1 verse 1: Our great God and saviour Jesus Christ.  This verse means that Christ is the saviour of all men in terms of his role. A.T. Robertsons commentary on this verse states that God is the potential saviour of all¹. J.C. Ryles exposition (on another passage relating directly to Christ) is very helpful in understanding this:

Christ is to the souls of men what the sun is to the world. He is the center and source of all spiritual light, warmth, life, health, growth, beauty, and fertility. Like the sun, He shines for the common benefit of all mankind--for high and for low, for rich and for poor, for Jew and for Greek. Like the sun, He is free to all. All may look at Him, and drink health out of His light. If millions of mankind were mad enough to dwell in caves underground, or to bandage their eyes, their darkness would be their own fault, and not the fault of the sun. So, likewise, if millions of men and women love spiritual "darkness rather than light," the blame must be laid on their blind hearts, and not on Christ. "Their foolish hearts are darkened." (John 3:19; Rom. 1:21.) But whether men will see or not, Christ is the true sun, and the light of the world. There is no light for sinners except in the Lord Jesus.²

Christ is the Saviour of all men in the sense that he provided salvation at the Cross. It was sufficient to cover the sins of the whole human race, but it’s effect can only be experienced by belief. A father is the provider for his family, but the children still have to eat that provision. If the child rejects it and starves, the father is still the provider. In the same way, man can reject Christ and go to eternal doom, yet he is still their saviour as he has already provided it for them.