Contradiction with John 15:19
Colossians 4:3 asks for a door to be opened for preaching, whereas John 15:19 implies separation from the world's acceptance.
John 15:19: If ye were of the world, the world would love his own: but because ye are not of the world, but I have chosen you out of the world, therefore the world hateth you.
Contradiction with Matthew 10:14
Colossians 4:3 speaks about an opportunity for ministry, while Matthew 10:14 suggests leaving those who do not receive the message.
Matthew 10:14: And whosoever shall not receive you, nor hear your words, when ye depart out of that house or city, shake off the dust of your feet.
Contradiction with Acts 18:6
In Colossians 4:3, there is a request for a chance to declare the gospel, but Acts 18:6 shows Paul turning away from those who opposed and rejected the message.
Acts 18:6: And when they opposed themselves, and blasphemed, he shook [his] raiment, and said unto them, Your blood [be] upon your own heads; I [am] clean: from henceforth I will go unto the Gentiles.
Contradiction with Matthew 7:6
Colossians 4:3 seeks an open door for spreading the gospel, contrasted by Matthew 7:6, which advises against giving what is holy to those who will not appreciate it.
Matthew 7:6: Give not that which is holy unto the dogs, neither cast ye your pearls before swine, lest they trample them under their feet, and turn again and rend you.
Contradiction with 2 Corinthians 6:14
Colossians 4:3 desires an opening to speak to non-believers, whereas 2 Corinthians 6:14 advises against being yoked with unbelievers.
2 Corinthians 6:14: Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness?