Hi arunangelo. That is quite a stark statement you made, "Therefore, we must never refuse to forgive others."
What if they are unrepentant? The Bible reveals that there is a lake of fire, into which unrepentant sinners will be thrown and destroyed by a loving God. Revelation 21:8, (NLT) says: "But cowards, unbelievers, the corrupt, murderers, the immoral, those who practice witchcraft, idol worshipers, and all liars, their fate is in the fiery lake of burning sulphur. This is the second death."
Many believe the Bible teaches that Christians should be forgiving all the time, but notice what Paul said in 1 Corinthians 5:13, (NLT) says: "God will judge those on the outside; but as the Scriptures say, 'You must remove the evil person from among you.'" Who was this evil or wicked person in the congregation and why was he not immediately forgiven. In fact, he was removed from the congregation. 1 Corinthians 5:1-7, shows this person committed serious immoral behaviour and was to be removed from the congregation, to protect the rest of the congregation from his corrupting influence. But, later in 2 Corinthians 2:5-9, Paul's comments show this person had changed and was remorseful, so he should now be let back into the congregation and be forgiven. Paul's inspired words show if a person commits serious immoral behaviour and is not repentant, they are not to be forgive, but put out of the congregation. Then, and only when they are repentant should they be allowed back in.
The Bible does not teach "Christians must never refuse to forgive others," even God will refuse to forgive those he destroys in the lake of burning sulphur.