2 Timothy 2:15
Study to shew thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth.
Firstly to study to show ourselves approved of God that we need not be ashamed means that we are doers of the word and not hearers only, baring our cross and partaking in the sufferings Christ, having faith God and truly following Christ and walking the walk. If we are doing this then we are doing the work and we'll be producing the fruits and we won't be ashamed!
The word of truth should be teaching us to turn from sin, not that we are in sinful flesh so we do sin and that's ok because Jesus has covered those sins and even if we still sin were ok with God(which I have heard from many in mainstream Christianity). That's not the truth, wilful sin is an abomination to God. The only way that Christ covers our sins is by the resurrection of Christ in our hearts by the spirit helping us to overcome sin and God sees his son in us and he's not seeing our flesh because we are dead to our old life and made alive in God being a new creation made without hands through Christ Jesus by the holy spirit of truth. Thus we are dead and our life is hidden with Christ in God (Colossians 3) and Christ is seen in us and through us.
Now go down a bit v18 onward
Nevertheless the foundation of God standeth sure, having this seal, The Lord knoweth them that are his. And, let every one that nameth the name of Christ depart from iniquity.
But in a great house there are not only vessels of gold and of silver, but also of wood and of earth; and some to honour, and some to dishonour.
If a man therefore purge himself from these, he shall be a vessel unto honour, sanctified, and meet for the master's use, and prepared unto every good work.
Flee also youthful lusts: but follow righteousness, faith, charity, peace, with them that call on the Lord out of a pure heart.
But foolish and unlearned questions avoid, knowing that they do gender strifes.
And the servant of the Lord must not strive; but be gentle unto all men, apt to teach, patient,
In meekness instructing those that oppose themselves; if God peradventure will give them repentance to the acknowledging of the truth; And that they may recover themselves out of the snare of the devil, who are taken captive by him at his will.
I have no need to call others names like dunce, or treat them as idiots etc. And I don't have the need to put anyone on ignore. If we belong to God, then God gives us a mouth to speak, and there will be no need to pull others down. Instead those who truly belong to God have the hope that all will get to know the truth and that all have the chance going to heaven, and they don't condemn others to hell either as I have seen some on here do, were not judges, and if we judge, then we are also judged by God. The word of God does the judging.
As for the un-circumcision and the circumcision. Those who truly belong to Christ are circumcised of the heart, and they are being led by the spirit, laying down their lives, they are dead to their old lives in the flesh and dying daily to sin as God strengthens them through Christ by the spirit to overcome, obeying God, turning from the sinful lusts the flesh and this world and they will be worshipping God in spirit and in truth.