It is not our place to condemn anyone. Treat them as Christ told us, "Love thy neighbor as thyself." Make sure that they know theat Christ died for them. Anything further is between them and God.
Since the question is in the context of the Bible, and those who follow the Bible that there is a drastic and almost revolutionary difference between the Old Testament or Covenant and the New, it is as certain as night follows day that the Old Testament laws as quoted in the above link simply
do not apply. Were this really to be so, then the gaols would be crowded with Christians who had tried to carry this out either successfully or unsuccessfully. Capital punishment for unbelief is long gone.
What does apply is the law of love as quoted above, although to many, Christians are in a sense a troublesome lot as they stand for something quite opposed to the world's way of doing things. To say also that Jesus is the only way is definitely offensive to some. But if there was only one medicine available to cure an incurable disease then it would be wrong of someone not to tell about. This is how Christians feel.
15 But sanctify the Lord God in your hearts: and be ready always to give an answer to every man that asketh you a reason of the hope that is in you with meekness and fear: Elsewhere, the words 'meekness and fear' are translated 'gentleness and reverence'. Probably the 'golden rule' would also apply here. Christians would wish to treat unbelievers in the same way that they themselves would expect, or hope to be treated. This of course is not to say that they will not stand up for the truth, but that they will consider the other side.
Perhaps a difficulty arises sometimes when discussions are held 'on-line' in that people really do not know each other and so make assumptions about a person on the basis of what they know about others who hold a similar view. A Christian may sometimes be a former skeptic or has already considered the arguments from that perspective, and so has valid and helpful answers. Or they may have studied the Bible regularly and so know it well and could contribute much to mutual understanding if allowed.