Here are some relevant definitions from Lewis and Short
To watch, guard, keep any thing:
To observe, respect, regard, attend to, heed, keep, comply with a law, precept, recommendation, etc.
The Gospel is not for spectators. It is Good News that changes us when we hear and respond to it. We become Christ's agents and representatives in the world, called and empowered to proclaim him by word and example.
In the parish I serve, I use a tagline from one of the baptismal vows "seeking and serving Christ in all persons." It's on all our stationery and every bulletin. I use this as shorthand for evangelization, both by sharing the story (by word) and serving our neighbor (by example). In both cases, the seeking is active. Jesus once said that the Son of man came to seek and save the lost. That's you and me.
Keeping, respecting, observing the Gospel means letting our lives be transformed by Jesus, so that all we say and do is a living witness to his love. And that love is for "all persons." No exceptions allowed.
The Eucharistic table where all are sought, served, and fed is a foretaste of the heavenly banquet and a sign that another world is possible, not as a substitute for what we now see but as its transfiguration. As we approach the Day of Pentecost, let us remember that it is the Holy Spirit, God's own love poured into our hearts, that makes this transformation possible. Even now, God is at work to make all things new.