A Samaritan was essentially the enemy of the Jew which is what makes the story so poignant.
As for how to interact with non believers, Paul talks about this in his letters to the Romans and the church in Corinth.
1 Corinthians 2:14 NIV
[14] The person without the Spirit does not accept the things that come from the Spirit of God but considers them foolishness, and cannot understand them because they are discerned only through the Spirit.
1 Corinthians 5:11-13 NIV
[11] But now I am writing to you that you must not associate with anyone who claims to be a brother or sister but is sexually immoral or greedy, an idolater or slanderer, a drunkard or swindler. Do not even eat with such people. [12] What business is it of mine to judge those outside the church? Are you not to judge those inside? [13] God will judge those outside. “Expel the wicked person from among you"
Romans 8:7-8 NIV
[7] The mind governed by the flesh is hostile to God; it does not submit to God’s law, nor can it do so. [8] Those who are in the realm of the flesh cannot please God.
The reason Christians are encouraged to bring the gospel to non believers is commonly referred to as the great commission. However this should be given and not forced .
Luke 9:5 NIV
[5] If people do not welcome you, leave their town and shake the dust off your feet as a testimony against them.”
2 Timothy 2:24-26 NIV
[24] And the Lord’s servant must not be quarrelsome but must be kind to everyone, able to teach, not resentful. [25] Opponents must be gently instructed, in the hope that God will grant them repentance leading them to a knowledge of the truth, [26] and that they will come to their senses and escape from the trap of the devil, who has taken them captive to do his will.
Even so, Christians should expect to be hated
John 15:18-19 NIV
[18] “If the world hates you, keep in mind that it hated me first. [19] If you belonged to the world, it would love you as its own. As it is, you do not belong to the world, but I have chosen you out of the world. That is why the world hates you.