It is the responsibility of every Muslim to guide others to the right path as much as possible and whenever there is a possibility of positive effect. If you feel that the unbeliever can listen or think and will not re act in a diverse way, then you should approach him with wisdom and good way as Allah ( SWT) says in Quran ( Invite to the Way of your Lord with wisdom and good preaching and discuss with in the best way) Sura 16, Verse 125.
inviting people to the True Faith is not an option but a necessity otherwise how people can be guided if the believers don't invite them.
Being negative and not doing any thing to invite unbelievers when there is a possibility of effect, is not accepted from a believer who understands his duty towards Islam.
There are many Hadeeths emphasizing on the importance of inviting people to the True Faith, stating that inviting to Islam brings the reward of a prophet to the person who invites one unbeliever if his invitation was not accepted, but if the invitation was accepted, the reward will be like the reward of all the prophets.
The believer who invites others to Islam with wisdom and good way, is following the practice of the prophets, that is why, he gets the reward of a prophet.