You share your most intimate relationship (your saving relationship with Christ) by engaging in a strong relationship with others.
-- Unfortunately, hell is full of people who had very strong friendships with Christians, but those Christians never told them that what they were doing was a sin that would eventually lead to hell if they didn't turn away from it.
The Christian didn't want to appear that they were judging so they never told them that Jesus loves that sinner as much as he loves them, and that that Christian was just as lost condemned in his sin until he gave his life to Christ.
They would rather hope that the "example" they set of Christ will be enough, forgetting that Christ Himself called for us to share His gospel.
Hate to break it to you, but living a "saving relationship with Christ" means proactively trying to save someone.
Peter, Paul, James, etc. all went out and said what Jesus expected, risking more than just alienating a friend. Why? Because that is what God calls us to do.
Love is NOT continually letting someone drive towards a fast-approaching cliff in hopes that they will see your hands over your eyes and the scared look on your face.
And no, that doesn't mean you approach them, yell "sinner!" and tell them if they don't change right now that all is lost.
I was saved because a friend who I rejected because he would no longer do the things I liked because he became a Christian, didn't just say, "I love you" and "Jesus loves you."
He would not go places that I went to that were dens of sin, and no longer would do many of the "fun" things that I would do because he knew them to be wrong.
But he would still come see me. Ask if he could share God with me, tell me how God changed his life so he no longer needed that sin, and eventually ended up - because of his proactivity - leading me to Christ.
If he would have done solely what you advocate, I would have wondered why I needed to bother becoming a Christian.
This is why witnessing to strangers rarely works.
-- Yet people have gone into countries they have never visited before, witnessing to people they have never seen before, and
thousands end up coming to Christ.
What you are saying is that Christ was wrong when he said to, "Preach the Gospel to all nations."
I have been part of ministries that head into the inner cities and Central American countries on mission trips to witness to "strangers."
Returning 3-6-9-12 months later it is heartening to see those people we had never seen before our last visit, growing in Jesus, witnessing to others, getting family members saved, starting churches of their own.
Witnessing out of love, with groundwork laid by sincere prayer changes peoples lives, in family, in friends, AND strangers.
Just "being their good friend" and "not letting them feel judged" is not even the bare minimum God calls us to do.